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• BizTalk: History of one project architecture

  - by Leonid Ganeline

  "In the beginning God made heaven and earth. Then he started to integrate." At the very start was the requirement: integrate two working systems. Small digging up: It was one system. It was good but IT guys want to change it to the new one, much better, chipper, more flexible, and more progressive in technologies, more suitable for the future, for the faster world and hungry competitors. One thing. One small, little thing. We cannot turn off the old system (call it A, because it was the first), turn on the new one (call it B, because it is second but not the last one). The A has a hundreds users all across a country, they must study B. A still has a lot nice custom features, home-made features that cannot disappear. These features have to be moved to the B and it is a long process, months and months of redevelopment. So, the decision was simple. Let’s move not jump, let’s both systems working side-by-side several months. In this time we could teach the users and move all custom A’s special functionality to B. That automatically means both systems should work side-by-side all these months and use the same data. Data in A and B must be in sync. That’s how the integration projects get birth. Moreover, the specific of the user tasks requires the both systems must be in sync in real-time. Nightly synchronization is not working, absolutely.   First draft The first draft seems simple. Both systems keep data in SQL databases. When data changes, the Create, Update, Delete operations performed on the data, and the sync process could be started. The obvious decision is to use triggers on tables. When we are talking about data, we are talking about several entities. For example, Orders and Items [in Orders]. We decided to use the BizTalk Server to synchronize systems. Why it was chosen is another story. Second draft   Let’s take an example how it works in more details. 1.       User creates a new entity in the A system. This fires an insert trigger on the entity table. Trigger has to pass the message “Entity created”. This message includes all attributes of the new entity, but I focused on the Id of this entity in the A system. Notation for this message is id.A. System A sends id.A to the BizTalk Server. 2.       BizTalk transforms id.A to the format of the system B. This is easiest part and I will not focus on this kind of transformations in the following text. The message on the picture is still id.A but it is in slightly different format, that’s why it is changing in color. BizTalk sends id.A to the system B. 3.       The system B creates the entity on its side. But it uses different id-s for entities, these id-s are id.B. System B saves id.A+id.B. System B sends the message id.A+id.B back to the BizTalk. 4.       BizTalk sends the message id.A+id.B to the system A. 5.       System A saves id.A+id.B. Why both id-s should be saved on both systems? It was one of the next requirements. Users of both systems have to know the systems are in sync or not in sync. Users working with the entity on the system A can see the id.B and use it to switch to the system B and work there with the copy of the same entity. The decision was to store the pairs of entity id-s on both sides. If there is only one id, the entities are not in sync yet (for the Create operation). Third draft Next problem was the reliability of the synchronization. The synchronizing process can be interrupted on each step, when message goes through the wires. It can be communication problem, timeout, temporary shutdown one of the systems, the second system cannot be synchronized by some internal reason. There were several potential problems that prevented from enclosing the whole synchronization process in one transaction. Decision was to restart the whole sync process if it was not finished (in case of the error). For this purpose was created an additional service. Let’s call it the Resync service. We still keep the id pairs in both systems, but only for the fast access not for the synchronization process. For the synchronizing these id-s now are kept in one main place, in the Resync service database. The Resync service keeps record as: ·       Id.A ·       Id.B ·       Entity.Type ·       Operation (Create, Update, Delete) ·       IsSyncStarted (true/false) ·       IsSyncFinished (true/false0 The example now looks like: 1.       System A creates id.A. id.A is saved on the A. Id.A is sent to the BizTalk. 2.       BizTalk sends id.A to the Resync and to the B. id.A is saved on the Resync. 3.       System B creates id.B. id.A+id.B are saved on the B. id.A+id.B are sent to the BizTalk. 4.       BizTalk sends id.A+id.B to the Resync and to the A. id.A+id.B are saved on the Resync. 5.       id.A+id.B are saved on the B. Resync changes the IsSyncStarted and IsSyncFinished flags accordingly. The Resync service implements three main methods: ·       Save (id.A, Entity.Type, Operation) ·       Save (id.A, id.B, Entity.Type, Operation) ·       Resync () Two Save() are used to save id-s to the service storage. See in the above example, in 2 and 4 steps. What about the Resync()? It is the method that finishes the interrupted synchronization processes. If Save() is started by the trigger event, the Resync() is working as an independent process. It periodically scans the Resync storage to find out “unfinished” records. Then it restarts the synchronization processes. It tries to synchronize them several times then gives up.     One more thing, both systems A and B must tolerate duplicates of one synchronizing process. Say on the step 3 the system B was not able to send id.A+id.B back. The Resync service must restart the synchronization process that will send the id.A to B second time. In this case system B must just send back again also created id.A+id.B pair without errors. That means “tolerate duplicates”. Fourth draft Next draft was created only because of the aesthetics. As it always happens, aesthetics gave significant performance gain to the whole system. First was the stupid question. Why do we need this additional service with special database? Can we just master the BizTalk to do something like this Resync() does? So the Resync orchestration is doing the same thing as the Resync service. It is started by the Id.A and finished by the id.A+id.B message. The first works as a Start message, the second works as a Finish message.     Here is a diagram the whole process without errors. It is pretty straightforward. The Resync orchestration is waiting for the Finish message specific period of time then resubmits the Id.A message. It resubmits the Id.A message specific number of times then gives up and gets suspended. It can be resubmitted then it starts the whole process again: waiting [, resubmitting [, get suspended]], finishing. Tuning up The Resync orchestration resubmits the id.A message with special “Resubmitted” flag. The subscription filter on the Resync orchestration includes predicate as (Resubmit_Flag != “Resubmitted”). That means only the first Sync orchestration starts the Resync orchestration. Other Sync orchestration instantiated by the resubmitting can finish this Resync orchestration but cannot start another instance of the Resync   Here is a diagram where system B was inaccessible for some period of time. The Resync orchestration resubmitted the id.A two times. Then system B got the response the id.A+id.B and this finished the Resync service execution. What is interesting about this, there were submitted several identical id.A messages and only one id.A+id.B message. Because of this, the system B and the Resync must tolerate the duplicate messages. We also told about this requirement for the system B. Now the same requirement is for the Resunc. Let’s assume the system B was very slow in the first response and the Resync service had time to resubmit two id.A messages. System B responded not, as it was in previous case, with one id.A+id.B but with two id.A+id.B messages. First of them finished the Resync execution for the id.A. What about the second id.A+id.B? Where it goes? So, we have to add one more internal requirement. The whole solution must tolerate many identical id.A+id.B messages. It is easy task with the BizTalk. I added the “SinkExtraMessages” subscriber (orchestration with one receive shape), that just get these messages and do nothing. Real design Real architecture is much more complex and interesting. In reality each system can submit several id.A almost simultaneously and completely unordered. There are not only the “Create entity” operation but the Update and Delete operations. And these operations relate each other. Say the Update operation after Delete means not the same as Update after Create. In reality there are entities related each other. Say the Order and Order Items. Change on one of it could start the series of the operations on another. Moreover, the system internals are the “black boxes” and we cannot predict the exact content and order of the operation series. It worth to say, I had to spend a time to manage the zombie message problems. The zombies are still here, but this is not a problem now. And this is another story. What is interesting in the last design? One orchestration works to help another to be more reliable. Why two orchestration design is more reliable, isn’t it something strange? The Synch orchestration takes all the message exchange between systems, here is the area where most of the errors could happen. The Resync orchestration sends and receives messages only within the BizTalk server. Is there another design? Sure. All Resync functionality could be implemented inside the Sync orchestration. Hey guys, some other ideas?

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• The Internet of Things & Commerce: Part 3 -- Interview with Kristen J. Flanagan, Commerce Product Management

  - by Katrina Gosek, Director | Commerce Product Strategy-Oracle

  Internet of Things & Commerce Series: Part 3 (of 3) And now for the final installment my three part series on the Internet of Things & Commerce. Post one, “The Next 7,000 Days”, introduced the idea of the Internet of Things, followed by a second post interviewing one of our chief commerce innovation strategists, Brian Celenza.  This final post in the series is an interview with Kristen J. Flanagan, lead product manager for Oracle Commerce omnichannel strategy. She takes us through the past, present, and future of how our Commerce Solution is re-imagining the way physical and digital shopping come together. ------- QUESTION: It’s your job to stay on top of what our customers’ need to not only run their online businesses effectively, but also to make sure they have product capabilities they can innovate and grow on. What key trend has been top-of-mind for you and our customers around this collision of physical and digital shopping? Kristen: I’ll agree with Brian Celenza that hands down mobile has forced a major disruption in shopping and selling behavior. A few years ago, mobile exploded at a pace I don't think anyone was expecting. Early on, we saw our customers scrambling to establish a mobile presence---mostly through "screen scraping" technologies. As smartphones continued to advance (at lightening speed!), our customers started to investigate ways to truly tap in to their eCommerce capabilities to deliver the mobile experience. They started looking to us for a means of using the eCommerce services and capabilities to deliver a mobile experience that is tailored for mobile rather than the desktop experience on a smaller screen. In the future, I think we'll see customers starting to really understand what their shoppers need and expect from a mobile offering and how they can adapt their content and delivery of that content to meet those needs. And, mobile shopping doesn’t stop at the consumer / buyer. Because the in-store experience is compelling and has advantages that digital just can't offer, we're also starting to see the eCommerce services being leveraged for mobile for in-store sales associates. Brick-and-mortar retailers are interested in putting the omnichannel product catalog, promotions, and cart into the hands of knowledgeable associates. Retailers are now looking to connect and harness the eCommerce data in-store so that shoppers have a reason to walk-in. I think we'll be seeing a lot more customers thinking about melding the in-store and digital experiences to present a richer offering for shoppers.    QUESTION: What are some examples of what our customers are doing currently to bring these concepts to reality? Kristen: Well, without question, connecting digital and brick-and-mortar worlds is becoming tablestakes for selling experiences. If a brand has a foot in both worlds (i.e., isn’t a pureplay online retailer), they have to connect the dots because shoppers – whether consumers or B2B buyers –don't think in clearly defined channels anymore. The expectation is connectedness – for on- and offline experiences, promotions, products, and customer data. What does this mean practically for businesses selling goods on- and offline? It touches a lot of systems: inventory info on the eCommerce site, fulfillment options across channels (buy online/pickup in store), order information (representing various channels for a cohesive view of shopper order history), promotions across digital and store, etc.  A few years ago, the main link between store and digital was the smartphone. We all remember when “apps” became a thing and many of our customers were scrambling to get a native app out there. Now we're seeing more strategic thinking around the benefits of mobile web vs. native and how that ties in to the purpose and role of mobile within the digital channel. Put it more broadly, how these pieces fit together in the overall brand puzzle.  The same could be said for “showrooming.” Where it was a major concern (i.e., shoppers using stores to look at merchandise and then order online from Amazon), in recent months, it’s emerged that the inverse is now becoming a a reality as well. "Webrooming" (using digital sites to do research before making a purchase in the store) is a new behavior pure play retailers are challenged with. There are many technologies, behaviors, and information that need to tie together to offer a holistic omnichannel shopping experience. As a result, brands are looking for ways to connect the digital and in-store experiences to bridge the gaps: shared assortments across channels, assisted selling apps that arm associates with information about shoppers, shared promotions, inventory, etc. QUESTION: How has Oracle Commerce been built to help brands make the link between in-store and digital over the last few years? Kristen: Over the last seven years, the product has been in step with the changes in industry needs. Here is a brief history of the evolution: Prior to Oracle’s acquisition of ATG and Endeca, key investments were made to cross-channel functionality that we are still building on today. Commerce Service Center (v2007.1) ATG introduced the Commerce Service Center in 2007.1 and marked the first entry into what was then called “cross-channel.” The Commerce Service Center is a call-center-agent-facing application that enables agents to see shopper orders, online catalog, promotions, and pricing. It is tightly integrated with the eCommerce capabilities of the platform and commerce engine and provided a means of connecting data from the call center and online channels.  REST services framework (v9.1)  In v9.1 we introduced the REST services framework and interface in the Platform that enabled customers to use ATG web services in other applications. This framework has become the basis for our subsequent omni-channel features and functionality. Multisite Architecture (v10) With the v10 release, we introduced the Multisite Architecture, which enabled customers to manage multiple sites (and channels) within a single instance of the BCC. Customers could create site- and channel-specific catalogs, promotions, targeters, and scenarios. Endeca Page Builder (2.x) / Experience Manager (3.x) With the introduction of Endeca for Mobile (now part of the core platform, available through the reference store – see blow) on top of Page Builder (and then eventually Experience Manager), Endeca gave business users the tools to create and manage native and mobile web applications. And since the acquisition of both ATG (2011) and Endeca (2012), Oracle Commerce has leveraged the best of each leading technology’s capabilities for omnichannel commerce to continue to drive innovation for our customers. Service enablement of core Oracle Commerce capabilities (v10.1.1, 10.2, & 11) After the establishment of the REST services framework and interface, we followed up in subsequent releases with service enablement of core Oracle Commerce capabilities throughout the iOS native app and the enablement of the core Commerce Service Center features. The result is that customers can leverage these services for their integrations with other systems, as well as their omnichannel initiatives.  Mobile web reference application (v10.1) In 10.1 we introduced the shopper-facing mobile reference application that showed how to use Oracle Commerce to deliver a mobile web experience for shoppers. This included the use of Experience Manager and cartridges to drive those experiences on select pages.  Native (iOS) reference application (v10.1.1)  We came out with the 10.1.1 shopper-facing native iOS ref app that illustrated how to use the Commerce REST services to deliver an iOS app. Also included Experience Manager-driven pages.   Assisted Selling reference application (v10.2.1)  The Assisted Selling reference application is our first reference application designed for the in-store associate. This iOS app shows customers how they can use Oracle Commerce data and information to provide a high-touch, consultative sales environment as well as to put the endless aisle into hands of their associates. Shoppers can start a cart online, and in-store associates can access that cart via the application to provide more information or add products and then transact using the ATG engine. Support for Retail promotions (v11) As part of the v11 release, we worked with teams in the Oracle Retail Global Business Unit (RGBU) to assess which promotion types and capabilities are supported across our products. Those products included Oracle Commerce, Oracle Point of Service (ORPOS), and Oracle Retail Price Management (RPM). The result is that customers can now more easily support omnichannel use cases between the store and digital.  Making sure Oracle Commerce can help support the omnichannel needs of our customers is core to our product strategy. With 89% of consumers now use two or more channels to make a single purchase, ensuring that cross-channel interactions are linked is critical to a great customer experience – and to sales. As Oracle Commerce evolves, we want to make it simple for organizations to create, deliver, and scale experiences across touchpoints with our create once, deploy commerce anywhere framework. We have a flexible, services-oriented architecture that allows data, content, catalogs, cart, experiences, personalization, and merchandising to be shared across touchpoints and easily extended in to new environments like mobile, social, in-store, Call Center, and new Websites. [For the latest downloads and Oracle Commerce documentation, please visit the Oracle Technical Network.] ------ Thank you to both Brian and Kristen for their contributions and to this blog series and their continued thought leadership for Oracle Commerce. We are all looking forward to the coming years of months of new shopping behaviors and opportunities to innovate. Because – if the digital fabric of our everyday lives continues to change at the same pace – the next five years (that just under 2,000 days), will be dramatic. ---------- THIS DOCUMENT IS FOR INFORMATIONAL PURPOSES ONLY AND MAY NOT BE INCORPORATED INTO A CONTRACT OR AGREEMENT

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• Solving Big Problems with Oracle R Enterprise, Part II

  - by dbayard

  Part II – Solving Big Problems with Oracle R Enterprise In the first post in this series (see https://blogs.oracle.com/R/entry/solving_big_problems_with_oracle), we showed how you can use R to perform historical rate of return calculations against investment data sourced from a spreadsheet.  We demonstrated the calculations against sample data for a small set of accounts.  While this worked fine, in the real-world the problem is much bigger because the amount of data is much bigger.  So much bigger that our approach in the previous post won’t scale to meet the real-world needs. From our previous post, here are the challenges we need to conquer: The actual data that needs to be used lives in a database, not in a spreadsheet The actual data is much, much bigger- too big to fit into the normal R memory space and too big to want to move across the network The overall process needs to run fast- much faster than a single processor The actual data needs to be kept secured- another reason to not want to move it from the database and across the network And the process of calculating the IRR needs to be integrated together with other database ETL activities, so that IRR’s can be calculated as part of the data warehouse refresh processes In this post, we will show how we moved from sample data environment to working with full-scale data.  This post is based on actual work we did for a financial services customer during a recent proof-of-concept. Getting started with the Database At this point, we have some sample data and our IRR function.  We were at a similar point in our customer proof-of-concept exercise- we had sample data but we did not have the full customer data yet.  So our database was empty.  But, this was easily rectified by leveraging the transparency features of Oracle R Enterprise (see https://blogs.oracle.com/R/entry/analyzing_big_data_using_the).  The following code shows how we took our sample data SimpleMWRRData and easily turned it into a new Oracle database table called IRR_DATA via ore.create().  The code also shows how we can access the database table IRR_DATA as if it was a normal R data.frame named IRR_DATA. If we go to sql*plus, we can also check out our new IRR_DATA table: At this point, we now have our sample data loaded in the database as a normal Oracle table called IRR_DATA.  So, we now proceeded to test our R function working with database data. As our first test, we retrieved the data from a single account from the IRR_DATA table, pull it into local R memory, then call our IRR function.  This worked.  No SQL coding required! Going from Crawling to Walking Now that we have shown using our R code with database-resident data for a single account, we wanted to experiment with doing this for multiple accounts.  In other words, we wanted to implement the split-apply-combine technique we discussed in our first post in this series.  Fortunately, Oracle R Enterprise provides a very scalable way to do this with a function called ore.groupApply().  You can read more about ore.groupApply() here: https://blogs.oracle.com/R/entry/analyzing_big_data_using_the1 Here is an example of how we ask ORE to take our IRR_DATA table in the database, split it by the ACCOUNT column, apply a function that calls our SimpleMWRR() calculation, and then combine the results. (If you are following along at home, be sure to have installed our myIRR package on your database server via  “R CMD INSTALL myIRR”). The interesting thing about ore.groupApply is that the calculation is not actually performed in my desktop R environment from which I am running.  What actually happens is that ore.groupApply uses the Oracle database to perform the work.  And the Oracle database is what actually splits the IRR_DATA table by ACCOUNT.  Then the Oracle database takes the data for each account and sends it to an embedded R engine running on the database server to apply our R function.  Then the Oracle database combines all the individual results from the calls to the R function. This is significant because now the embedded R engine only needs to deal with the data for a single account at a time.  Regardless of whether we have 20 accounts or 1 million accounts or more, the R engine that performs the calculation does not care.  Given that normal R has a finite amount of memory to hold data, the ore.groupApply approach overcomes the R memory scalability problem since we only need to fit the data from a single account in R memory (not all of the data for all of the accounts). Additionally, the IRR_DATA does not need to be sent from the database to my desktop R program.  Even though I am invoking ore.groupApply from my desktop R program, because the actual SimpleMWRR calculation is run by the embedded R engine on the database server, the IRR_DATA does not need to leave the database server- this is both a performance benefit because network transmission of large amounts of data take time and a security benefit because it is harder to protect private data once you start shipping around your intranet. Another benefit, which we will discuss in a few paragraphs, is the ability to leverage Oracle database parallelism to run these calculations for dozens of accounts at once. From Walking to Running ore.groupApply is rather nice, but it still has the drawback that I run this from a desktop R instance.  This is not ideal for integrating into typical operational processes like nightly data warehouse refreshes or monthly statement generation.  But, this is not an issue for ORE.  Oracle R Enterprise lets us run this from the database using regular SQL, which is easily integrated into standard operations.  That is extremely exciting and the way we actually did these calculations in the customer proof. As part of Oracle R Enterprise, it provides a SQL equivalent to ore.groupApply which it refers to as “rqGroupEval”.  To use rqGroupEval via SQL, there is a bit of simple setup needed.  Basically, the Oracle Database needs to know the structure of the input table and the grouping column, which we are able to define using the database’s pipeline table function mechanisms. Here is the setup script: At this point, our initial setup of rqGroupEval is done for the IRR_DATA table.  The next step is to define our R function to the database.  We do that via a call to ORE’s rqScriptCreate. Now we can test it.  The SQL you use to run rqGroupEval uses the Oracle database pipeline table function syntax.  The first argument to irr_dataGroupEval is a cursor defining our input.  You can add additional where clauses and subqueries to this cursor as appropriate.  The second argument is any additional inputs to the R function.  The third argument is the text of a dummy select statement.  The dummy select statement is used by the database to identify the columns and datatypes to expect the R function to return.  The fourth argument is the column of the input table to split/group by.  The final argument is the name of the R function as you defined it when you called rqScriptCreate(). The Real-World Results In our real customer proof-of-concept, we had more sophisticated calculation requirements than shown in this simplified blog example.  For instance, we had to perform the rate of return calculations for 5 separate time periods, so the R code was enhanced to do so.  In addition, some accounts needed a time-weighted rate of return to be calculated, so we extended our approach and added an R function to do that.  And finally, there were also a few more real-world data irregularities that we needed to account for, so we added logic to our R functions to deal with those exceptions.  For the full-scale customer test, we loaded the customer data onto a Half-Rack Exadata X2-2 Database Machine.  As our half-rack had 48 physical cores (and 96 threads if you consider hyperthreading), we wanted to take advantage of that CPU horsepower to speed up our calculations.  To do so with ORE, it is as simple as leveraging the Oracle Database Parallel Query features.  Let’s look at the SQL used in the customer proof: Notice that we use a parallel hint on the cursor that is the input to our rqGroupEval function.  That is all we need to do to enable Oracle to use parallel R engines. Here are a few screenshots of what this SQL looked like in the Real-Time SQL Monitor when we ran this during the proof of concept (hint: you might need to right-click on these images to be able to view the images full-screen to see the entire image): From the above, you can notice a few things (numbers 1 thru 5 below correspond with highlighted numbers on the images above.  You may need to right click on the above images and view the images full-screen to see the entire image): The SQL completed in 110 seconds (1.8minutes) We calculated rate of returns for 5 time periods for each of 911k accounts (the number of actual rows returned by the IRRSTAGEGROUPEVAL operation) We accessed 103m rows of detailed cash flow/market value data (the number of actual rows returned by the IRR_STAGE2 operation) We ran with 72 degrees of parallelism spread across 4 database servers Most of our 110seconds was spent in the “External Procedure call” event On average, we performed 8,200 executions of our R function per second (110s/911k accounts) On average, each execution was passed 110 rows of data (103m detail rows/911k accounts) On average, we did 41,000 single time period rate of return calculations per second (each of the 8,200 executions of our R function did rate of return calculations for 5 time periods) On average, we processed over 900,000 rows of database data in R per second (103m detail rows/110s) R + Oracle R Enterprise: Best of R + Best of Oracle Database This blog post series started by describing a real customer problem: how to perform a lot of calculations on a lot of data in a short period of time.  While standard R proved to be a very good fit for writing the necessary calculations, the challenge of working with a lot of data in a short period of time remained. This blog post series showed how Oracle R Enterprise enables R to be used in conjunction with the Oracle Database to overcome the data volume and performance issues (as well as simplifying the operations and security issues).  It also showed that we could calculate 5 time periods of rate of returns for almost a million individual accounts in less than 2 minutes. In a future post, we will take the same R function and show how Oracle R Connector for Hadoop can be used in the Hadoop world.  In that next post, instead of having our data in an Oracle database, our data will live in Hadoop and we will how to use the Oracle R Connector for Hadoop and other Oracle Big Data Connectors to move data between Hadoop, R, and the Oracle Database easily.

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• Using SPServices &amp; jQuery to Find My Stuff from Multi-Select Person/Group Field

  - by Mark Rackley

  Okay… quick blog post for all you SPServices fans out there. I needed to quickly write a script that would return all the tasks currently assigned to me.  I also wanted it to return any task that was assigned to a group I belong to. This can actually be done with a CAML query, so no big deal, right?  The rub is that the “assigned to” field is a multi-select person or group field. As far as I know (and I actually know so little) you cannot just write a CAML query to return this information. If you can, please leave a comment below and disregard the rest of this blog post… So… what’s a hacker to do? As always, I break things down to their most simple components (I really love the KISS principle and would get it tattooed on my back if people wouldn’t think it meant “Knights In Satan’s Service”. You really gotta be an old far to get that reference).  Here’s what we’re going to do: Get currently logged in user’s name as it is stored in a person field Find all the SharePoint groups the current user belongs to Retrieve a set of assigned tasks from the task list and then find those that are assigned to current  user or group current user belongs to Nothing too hairy… So let’s get started Some Caveats before I continue There are some obvious performance implications with this solution as I make a total of four SPServices calls and there’s a lot of looping going on. Also, the CAML query in this blog has NOT been optimized. If you move forward with this code, tweak it so that it returns a further subset of data or you will see horrible performance if you have a few hundred entries in your task list. Add a date range to the CAML or something. Find some way to limit the results as much as possible. Lastly, if you DO have a better solution, I would like you to share. Iron sharpens iron and all…   Alright, let’s really get started. Get currently logged in user’s name as it is stored in a person field First thing we need to do is understand how a person group looks when you look at the XML returned from a SharePoint Web Service call. It turns out it’s stored like any other multi select item in SharePoint which is <id>;#<value> and when you assign a person to that field the <value> equals the person’s name “Mark Rackley” in my case. This is for Windows Authentication, I would expect this to be different in FBA, but I’m not using FBA. If you want to know what it looks like with FBA you can use the code in this blog and strategically place an alert to see the value.  Anyway… I need to find the name of the user who is currently logged in as it is stored in the person field. This turns out to be one SPServices call: var userName = $().SPServices.SPGetCurrentUser({                     fieldName: "Title",                     debug: false                     }); As you can see, the “Title” field has the information we need. I suspect (although again, I haven’t tried) that the Title field also contains the user’s name as we need it if I was using FBA. Okay… last thing we need to do is store our users name in an array for processing later: myGroups = new Array(); myGroups.push(userName); Find all the SharePoint groups the current user belongs to Now for the groups. How are groups returned in that XML stream?  Same as the person <ID>;#<Group Name>, and if it’s a mutli select it’s all returned in one big long string “<ID>;#<Group Name>;#<ID>;#<Group Name>;#<ID>;#<Group Name>;#<ID>;#<Group Name>;#<ID>;#<Group Name>”.  So, how do we find all the groups the current user belongs to? This is also a simple SPServices call. Using the “GetGroupCollectionFromUser” operation we can find all the groups a user belongs to. So, let’s execute this method and store all our groups. $().SPServices({       operation: "GetGroupCollectionFromUser",       userLoginName: $().SPServices.SPGetCurrentUser(),       async: false,       completefunc: function(xData, Status) {          $(xData.responseXML).find("[nodeName=Group]").each(function() {                 myGroups.push($(this).attr("Name"));          });         }     }); So, all we did in the above code was execute the “GetGroupCollectionFromUser” operation and look for the each “Group” node (row) and store the name for each group in our array that we put the user’s name in previously (myGroups). Now we have an array that contains the current user’s name as it will appear in the person field XML and  all the groups the current user belongs to. The Rest Now comes the easy part for all of you familiar with SPServices. We are going to retrieve our tasks from the Task list using “GetListItems” and look at each entry to see if it belongs to this person. If it does belong to this person we are going to store it for later processing. That code looks something like this: // get list of assigned tasks that aren't closed... *modify the CAML to perform better!*             $().SPServices({                   operation: "GetListItems",                   async: false,                   listName: "Tasks",                   CAMLViewFields: "<ViewFields>" +                             "<FieldRef Name='AssignedTo' />" +                             "<FieldRef Name='Title' />" +                             "<FieldRef Name='StartDate' />" +                             "<FieldRef Name='EndDate' />" +                             "<FieldRef Name='Status' />" +                             "</ViewFields>",                   CAMLQuery: "<Query><Where><And><IsNotNull><FieldRef Name='AssignedTo'/></IsNotNull><Neq><FieldRef Name='Status'/><Value Type='Text'>Completed</Value></Neq></And></Where></Query>",                     completefunc: function (xData, Status) {                         var aDataSet = new Array();                        //loop through each returned Task                         $(xData.responseXML).find("[nodeName=z:row]").each(function() {                             //store the multi-select string of who task is assigned to                             var assignedToString = $(this).attr("ows_AssignedTo");                             found = false;                            //loop through the persons name and all the groups they belong to                             for(var i=0; i<myGroups.length; i++) {                                 //if the person's name or group exists in the assigned To string                                 //then the task is assigned to them                                 if (assignedToString.indexOf(myGroups[i]) >= 0){                                     found = true;                                     break;                                 }                             }                             //if the Task belongs to this person then store or display it                             //(I'm storing it in an array)                             if (found){                                 var thisName = $(this).attr("ows_Title");                                 var thisStartDate = $(this).attr("ows_StartDate");                                 var thisEndDate = $(this).attr("ows_EndDate");                                 var thisStatus = $(this).attr("ows_Status");                                                                  var aDataRow=new Array(                                     thisName,                                     thisStartDate,                                     thisEndDate,                                     thisStatus);                                 aDataSet.push(aDataRow);                             }                          });                          SomeFunctionToDisplayData(aDataSet);                     }                 }); Some notes on why I did certain things and additional caveats. You will notice in my code that I’m doing an AssignedToString.indexOf(GroupName) to see if the task belongs to the person. This could possibly return bad results if you have SharePoint Group names that are named in such a way that the “IndexOf” returns a false positive.  For example if you have a Group called “My Users” and a group called “My Users – SuperUsers” then if a user belonged to “My Users” it would return a false positive on executing “My Users – SuperUsers”.IndexOf(“My Users”). Make sense? Just be aware of this when naming groups, we don’t have this problem. This is where also some fine-tuning can probably be done by those smarter than me. This is a pretty inefficient method to determine if a task belongs to a user, I mean what if a user belongs to 20 groups? That’s a LOT of looping.  See all the opportunities I give you guys to do something fun?? Also, why am I storing my values in an array instead of just writing them out to a Div? Well.. I want to pass my data to a jQuery library to format it all nice and pretty and an Array is a great way to do that. When all is said and done and we put all the code together it looks like:   $(document).ready(function() {         var userName = $().SPServices.SPGetCurrentUser({                     fieldName: "Title",                     debug: false                     });         myGroups = new Array();     myGroups.push(userName );       $().SPServices({       operation: "GetGroupCollectionFromUser",       userLoginName: $().SPServices.SPGetCurrentUser(),       async: false,       completefunc: function(xData, Status) {          $(xData.responseXML).find("[nodeName=Group]").each(function() {                 myGroups.push($(this).attr("Name"));          });                      // get list of assigned tasks that aren't closed... *modify this CAML to perform better!*             $().SPServices({                   operation: "GetListItems",                   async: false,                   listName: "Tasks",                   CAMLViewFields: "<ViewFields>" +                             "<FieldRef Name='AssignedTo' />" +                             "<FieldRef Name='Title' />" +                             "<FieldRef Name='StartDate' />" +                             "<FieldRef Name='EndDate' />" +                             "<FieldRef Name='Status' />" +                             "</ViewFields>",                   CAMLQuery: "<Query><Where><And><IsNotNull><FieldRef Name='AssignedTo'/></IsNotNull><Neq><FieldRef Name='Status'/><Value Type='Text'>Completed</Value></Neq></And></Where></Query>",                     completefunc: function (xData, Status) {                         var aDataSet = new Array();                         //loop through each returned Task                         $(xData.responseXML).find("[nodeName=z:row]").each(function() {                             //store the multi-select string of who task is assigned to                             var assignedToString = $(this).attr("ows_AssignedTo");                             found = false;                            //loop through the persons name and all the groups they belong to                             for(var i=0; i<myGroups.length; i++) {                                 //if the person's name or group exists in the assigned To string                                 //then the task is assigned to them                                 if (assignedToString.indexOf(myGroups[i]) >= 0){                                     found = true;                                     break;                                 }                             }                            //if the Task belongs to this person then store or display it                             //(I'm storing it in an array)                             if (found){                                 var thisName = $(this).attr("ows_Title");                                 var thisStartDate = $(this).attr("ows_StartDate");                                 var thisEndDate = $(this).attr("ows_EndDate");                                 var thisStatus = $(this).attr("ows_Status");                                                                  var aDataRow=new Array(                                     thisName,                                     thisStartDate,                                     thisEndDate,                                     thisStatus);                                 aDataSet.push(aDataRow);                             }                          });                          SomeFunctionToDisplayData(aDataSet);                     }                 });       }    });  }); Final Thoughts So, there you have it. Take it and run with it. Make it something cool (and tell me how you did it). Another possible way to improve performance in this scenario is to use a DVWP to display the tasks and use jQuery and the “myGroups” array from this blog post to hide all those rows that don’t belong to the current user. I haven’t tried it, but it does move some of the processing off to the server (generating the view) so it may perform better.  As always, thanks for stopping by… hope you have a Merry Christmas…

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• Log Blog

  - by PointsToShare

  © 2011 By: Dov Trietsch. All rights reserved Logging – A log blog In a another blog (Missing Fields and Defaults) I spoke about not doing a blog about log files, but then I looked at it again and realized that this is a nice opportunity to show a simple yet powerful tool and also deal with static variables and functions in C#. My log had to be able to answer a few simple logging rules:   To log or not to log? That is the question – Always log! That is the answer  Do we share a log? Even when a file is opened with a minimal lock, it does not share well and performance greatly suffers. So sharing a log is not a good idea. Also, when sharing, it is harder to find your particular entries and you have to establish rules about retention. My recommendation – Do Not Share!  How verbose? Your log can be very verbose – a good thing when testing, very terse – a good thing in day-to-day runs, or somewhere in between. You must be the judge. In my Blog, I elect to always report a run with start and end times, and always report errors. I normally use 5 levels of logging: 4 – write all, 3 – write more, 2 – write some, 1 – write errors and timing, 0 – write none. The code sample below is more general than that. It uses the config file to set the max log level and each call to the log assigns a level to the call itself. If the level is above the .config highest level, the line will not be written. Programmers decide which log belongs to which level and thus we can set the .config differently for production and testing.  Where do I keep the log? If your career is important to you, discuss this with the boss and with the system admin. We keep logs in the L: drive of our server and make sure that we have a directory for each app that needs a log. When adding a new app, add a new directory. The default location for the log is also found in the .config file Print One or Many? There are two options here:   1.     Print many, Open but once once – you start the stream and close it only when the program ends. This is what you can do when you perform in “batch” mode like in a console app or a stsadm extension.The advantage to this is that starting a closing a stream is expensive and time consuming and because we use a unique file, keeping it open for a long time does not cause contention problems. 2.     Print one entry at a time or Open many – every time you write a line, you start the stream, write to it and close it. This work for event receivers, feature receivers, and web parts. Here scalability requires us to create objects on the fly and get rid of them as soon as possible.  A default value of the onceOrMany resides in the .config.  All of the above applies to any windows or web application, not just SharePoint.  So as usual, here is a routine that does it all, and a few simple functions that call it for a variety of purposes.   So without further ado, here is app.config  <?xml version="1.0" encoding="utf-8" ?> <configuration>     <configSections>         <sectionGroup name="applicationSettings" type="System.Configuration.ApplicationSettingsGroup, System, Version=2.0.0.0, Culture=neutral, ublicKeyToken=b77a5c561934e089" >         <section name="statics.Properties.Settings" type="System.Configuration.ClientSettingsSection, System, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" requirePermission="false" />         </sectionGroup>     </configSections>     <applicationSettings>         <statics.Properties.Settings>             <setting name="oneOrMany" serializeAs="String">                 <value>False</value>             </setting>             <setting name="logURI" serializeAs="String">                 <value>C:\staticLog.txt</value>             </setting>             <setting name="highestLevel" serializeAs="String">                 <value>2</value>             </setting>         </statics.Properties.Settings>     </applicationSettings> </configuration>   And now the code:  In order to persist the variables between calls and also to be able to persist (or not to persist) the log file itself, I created an EventLog class with static variables and functions. Static functions do not need an instance of the class in order to work. If you ever wondered why our Main function is static, the answer is that something needs to run before instantiation so that other objects may be instantiated, and this is what the “static” Main does. The various logging functions and variables are created as static because they do not need instantiation and as a fringe benefit they remain un-destroyed between calls. The Main function here is just used for testing. Note that it does not instantiate anything, just uses the log functions. This is possible because the functions are static. Also note that the function calls are of the form: Class.Function.  using System; using System.Collections.Generic; using System.Linq; using System.Text; using System.IO; namespace statics {       class Program     {         static void Main(string[] args)         {             //write a single line             EventLog.LogEvents("ha ha", 3, "C:\\hahafile.txt", 4, true, false);             //this single line will not be written because the msgLevel is too high             EventLog.LogEvents("baba", 3, "C:\\babafile.txt", 2, true, false);             //The next 4 lines will be written in succession - no closing             EventLog.LogLine("blah blah", 1);             EventLog.LogLine("da da", 1);             EventLog.LogLine("ma ma", 1);             EventLog.LogLine("lah lah", 1);             EventLog.CloseLog(); // log will close             //now with specific functions             EventLog.LogSingleLine("one line", 1);             //this is just a test, the log is already closed             EventLog.CloseLog();         }     }     public class EventLog     {         public static string logURI = Properties.Settings.Default.logURI;         public static bool isOneLine = Properties.Settings.Default.oneOrMany;         public static bool isOpen = false;         public static int highestLevel = Properties.Settings.Default.highestLevel;         public static StreamWriter sw;         /// <summary>         /// the program will "print" the msg into the log         /// unless msgLevel is > msgLimit         /// onceOrMany is true when once - the program will open the log         /// print the msg and close the log. False when many the program will         /// keep the log open until close = true         /// normally all the arguments will come from the app.config         /// called by many overloads of logLine         /// </summary>         /// <param name="msg"></param>         /// <param name="msgLevel"></param>         /// <param name="logFileName"></param>         /// <param name="msgLimit"></param>         /// <param name="onceOrMany"></param>         /// <param name="close"></param>         public static void LogEvents(string msg, int msgLevel, string logFileName, int msgLimit, bool oneOrMany, bool close)         {             //to print or not to print             if (msgLevel <= msgLimit)             {                 //open the file. from the argument (logFileName) or from the config (logURI)                 if (!isOpen)                 {                     string logFile = logFileName;                     if (logFileName == "")                     {                         logFile = logURI;                     }                     sw = new StreamWriter(logFile, true);                     sw.WriteLine("Started At: " + DateTime.Now.ToString("yyyy-MM-dd HH:mm:ss"));                     isOpen = true;                 }                 //print                 sw.WriteLine(msg);             }             //close when instructed             if (close || oneOrMany)             {                 if (isOpen)                 {                     sw.WriteLine("Ended At: " + DateTime.Now.ToString("yyyy-MM-dd HH:mm:ss"));                     sw.Close();                     isOpen = false;                 }             }         }           /// <summary>         /// The simplest, just msg and level         /// </summary>         /// <param name="msg"></param>         /// <param name="msgLevel"></param>         public static void LogLine(string msg, int msgLevel)         {             //use the given msg and msgLevel and all others are defaults             LogEvents(msg, msgLevel, "", highestLevel, isOneLine, false);         }                 /// <summary>         /// one line at a time - open print close         /// </summary>         /// <param name="msg"></param>         /// <param name="msgLevel"></param>         public static void LogSingleLine(string msg, int msgLevel)         {             LogEvents(msg, msgLevel, "", highestLevel, true, true);         }           /// <summary>         /// used to close. high level, low limit, once and close are set         /// </summary>         /// <param name="close"></param>         public static void CloseLog()         {             LogEvents("", 15, "", 1, true, true);         }           }     }   }   That’s all folks!

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• Matrix Multiplication with C++ AMP

  - by Daniel Moth

  As part of our API tour of C++ AMP, we looked recently at parallel_for_each. I ended that post by saying we would revisit parallel_for_each after introducing array and array_view. Now is the time, so this is part 2 of parallel_for_each, and also a post that brings together everything we've seen until now. The code for serial and accelerated Consider a naïve (or brute force) serial implementation of matrix multiplication  0: void MatrixMultiplySerial(std::vector<float>& vC, const std::vector<float>& vA, const std::vector<float>& vB, int M, int N, int W) 1: { 2: for (int row = 0; row < M; row++) 3: { 4: for (int col = 0; col < N; col++) 5: { 6: float sum = 0.0f; 7: for(int i = 0; i < W; i++) 8: sum += vA[row * W + i] * vB[i * N + col]; 9: vC[row * N + col] = sum; 10: } 11: } 12: } We notice that each loop iteration is independent from each other and so can be parallelized. If in addition we have really large amounts of data, then this is a good candidate to offload to an accelerator. First, I'll just show you an example of what that code may look like with C++ AMP, and then we'll analyze it. It is assumed that you included at the top of your file #include <amp.h> 13: void MatrixMultiplySimple(std::vector<float>& vC, const std::vector<float>& vA, const std::vector<float>& vB, int M, int N, int W) 14: { 15: concurrency::array_view<const float,2> a(M, W, vA); 16: concurrency::array_view<const float,2> b(W, N, vB); 17: concurrency::array_view<concurrency::writeonly<float>,2> c(M, N, vC); 18: concurrency::parallel_for_each(c.grid, 19: [=](concurrency::index<2> idx) restrict(direct3d) { 20: int row = idx[0]; int col = idx[1]; 21: float sum = 0.0f; 22: for(int i = 0; i < W; i++) 23: sum += a(row, i) * b(i, col); 24: c[idx] = sum; 25: }); 26: } First a visual comparison, just for fun: The beginning and end is the same, i.e. lines 0,1,12 are identical to lines 13,14,26. The double nested loop (lines 2,3,4,5 and 10,11) has been transformed into a parallel_for_each call (18,19,20 and 25). The core algorithm (lines 6,7,8,9) is essentially the same (lines 21,22,23,24). We have extra lines in the C++ AMP version (15,16,17). Now let's dig in deeper. Using array_view and extent When we decided to convert this function to run on an accelerator, we knew we couldn't use the std::vector objects in the restrict(direct3d) function. So we had a choice of copying the data to the the concurrency::array<T,N> object, or wrapping the vector container (and hence its data) with a concurrency::array_view<T,N> object from amp.h – here we used the latter (lines 15,16,17). Now we can access the same data through the array_view objects (a and b) instead of the vector objects (vA and vB), and the added benefit is that we can capture the array_view objects in the lambda (lines 19-25) that we pass to the parallel_for_each call (line 18) and the data will get copied on demand for us to the accelerator. Note that line 15 (and ditto for 16 and 17) could have been written as two lines instead of one: extent<2> e(M, W); array_view<const float, 2> a(e, vA); In other words, we could have explicitly created the extent object instead of letting the array_view create it for us under the covers through the constructor overload we chose. The benefit of the extent object in this instance is that we can express that the data is indeed two dimensional, i.e a matrix. When we were using a vector object we could not do that, and instead we had to track via additional unrelated variables the dimensions of the matrix (i.e. with the integers M and W) – aren't you loving C++ AMP already? Note that the const before the float when creating a and b, will result in the underling data only being copied to the accelerator and not be copied back – a nice optimization. A similar thing is happening on line 17 when creating array_view c, where we have indicated that we do not need to copy the data to the accelerator, only copy it back. The kernel dispatch On line 18 we make the call to the C++ AMP entry point (parallel_for_each) to invoke our parallel loop or, as some may say, dispatch our kernel. The first argument we need to pass describes how many threads we want for this computation. For this algorithm we decided that we want exactly the same number of threads as the number of elements in the output matrix, i.e. in array_view c which will eventually update the vector vC. So each thread will compute exactly one result. Since the elements in c are organized in a 2-dimensional manner we can organize our threads in a two-dimensional manner too. We don't have to think too much about how to create the first argument (a grid) since the array_view object helpfully exposes that as a property. Note that instead of c.grid we could have written grid<2>(c.extent) or grid<2>(extent<2>(M, N)) – the result is the same in that we have specified M*N threads to execute our lambda. The second argument is a restrict(direct3d) lambda that accepts an index object. Since we elected to use a two-dimensional extent as the first argument of parallel_for_each, the index will also be two-dimensional and as covered in the previous posts it represents the thread ID, which in our case maps perfectly to the index of each element in the resulting array_view. The kernel itself The lambda body (lines 20-24), or as some may say, the kernel, is the code that will actually execute on the accelerator. It will be called by M*N threads and we can use those threads to index into the two input array_views (a,b) and write results into the output array_view ( c ). The four lines (21-24) are essentially identical to the four lines of the serial algorithm (6-9). The only difference is how we index into a,b,c versus how we index into vA,vB,vC. The code we wrote with C++ AMP is much nicer in its indexing, because the dimensionality is a first class concept, so you don't have to do funny arithmetic calculating the index of where the next row starts, which you have to do when working with vectors directly (since they store all the data in a flat manner). I skipped over describing line 20. Note that we didn't really need to read the two components of the index into temporary local variables. This mostly reflects my personal choice, in some algorithms to break down the index into local variables with names that make sense for the algorithm, i.e. in this case row and col. In other cases it may i,j,k or x,y,z, or M,N or whatever. Also note that we could have written line 24 as: c(idx[0], idx[1])=sum  or  c(row, col)=sum instead of the simpler c[idx]=sum Targeting a specific accelerator Imagine that we had more than one hardware accelerator on a system and we wanted to pick a specific one to execute this parallel loop on. So there would be some code like this anywhere before line 18: vector<accelerator> accs = MyFunctionThatChoosesSuitableAccelerators(); accelerator acc = accs[0]; …and then we would modify line 18 so we would be calling another overload of parallel_for_each that accepts an accelerator_view as the first argument, so it would become: concurrency::parallel_for_each(acc.default_view, c.grid, ...and the rest of your code remains the same… how simple is that? Comments about this post by Daniel Moth welcome at the original blog.

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• Linux Kernel crash mutex_lock_slowpath "blocked for more than 120 seconds". What to do?

  - by Roddick

  I have out-of-the box Debian Lenny with non-custom kernel 2.6.26-2-amd64. Brand new server that is used to 5% of it's potential, CPU and Disk-wise. Meaning it probably not crashing because of overload. every few days it freezes with hundreds of these messages in console log: : [284847.828428] INFO: task apache2:12473 blocked for more than 120 seconds. : [284847.868468] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. : [284847.912759] apache2 D ffff8101bc6b7ab0 0 12473 14358 : [284847.912763] ffff810160d5bc50 0000000000000082 ffff8101c0002e40 0000000000000000 : [284847.912766] ffff8101a7c42950 ffff810327d92810 ffff8101a7c42bd8 0000000400000044 : [284847.912770] ffff8101c0002e40 00000000000612d0 0000000000000000 00000040000612d0 : [284847.912773] Call Trace: : [284847.912786] [<ffffffff80429b0d>] __mutex_lock_slowpath+0x64/0x9b : [284847.912790] [<ffffffff80429972>] mutex_lock+0xa/0xb : [284847.912794] [<ffffffff802a20b9>] do_lookup+0x82/0x1c1 : [284847.912800] [<ffffffff802a4271>] __link_path_walk+0x87a/0xd19 : [284847.912805] [<ffffffff80295844>] kmem_getpages+0x96/0x15f : [284847.912808] [<ffffffff80295fb7>] ____cache_alloc_node+0x6d/0x106 : [284847.912814] [<ffffffff802a4756>] path_walk+0x46/0x8b : [284847.912819] [<ffffffff802a4a82>] do_path_lookup+0x158/0x1cf : [284847.912822] [<ffffffff802a3879>] getname+0x140/0x1a7 : [284847.912827] [<ffffffff802a53f1>] __user_walk_fd+0x37/0x4c : [284847.912831] [<ffffffff8029e381>] vfs_lstat_fd+0x18/0x47 : [284847.912840] [<ffffffff8029e3c9>] sys_newlstat+0x19/0x31 : [284847.912848] [<ffffffff8020beda>] system_call_after_swapgs+0x8a/0x8f Almost all traces has __mutex_lock_slowpath as top-level. Only some has different trace: : [284847.737386] INFO: task apache2:12472 blocked for more than 120 seconds. : [284847.777551] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. : [284847.824881] apache2 D ffff8101bc6b7ab0 0 12472 14358 : [284847.824886] ffff8101b9cc1c50 0000000000000086 ffffffffa0131e0a 0000000000000002 : [284847.824889] ffff8102e7454300 ffff810324c6cad0 ffff8102e7454588 0000000000000000 : [284847.824893] 0000000000000001 0000000000000296 0000000000000003 ffff8101b9cc1c58 : [284847.824896] Call Trace: : [284847.828403] [<ffffffffa0131e0a>] :ext3:__ext3_journal_dirty_metadata+0x1e/0x46 : [284847.828412] [<ffffffff80429b0d>] __mutex_lock_slowpath+0x64/0x9b : [284847.828418] [<ffffffff80429972>] mutex_lock+0xa/0xb : [284847.828421] [<ffffffff802a20b9>] do_lookup+0x82/0x1c1 : [284847.828427] [<ffffffff802a4271>] __link_path_walk+0x87a/0xd19 : [284847.828428] [<ffffffff80271296>] find_lock_page+0x1f/0x8a : [284847.828428] [<ffffffff80273182>] filemap_fault+0x1c2/0x33c : [284847.828428] [<ffffffff802a4756>] path_walk+0x46/0x8b : [284847.828428] [<ffffffff802a4a82>] do_path_lookup+0x158/0x1cf : [284847.828428] [<ffffffff802a3879>] getname+0x140/0x1a7 : [284847.828428] [<ffffffff802a53f1>] __user_walk_fd+0x37/0x4c : [284847.828428] [<ffffffff8029e381>] vfs_lstat_fd+0x18/0x47 : [284847.828428] [<ffffffff8029e3c9>] sys_newlstat+0x19/0x31 : [284847.828428] [<ffffffff8020beda>] system_call_after_swapgs+0x8a/0x8f kernel: [1912668.466347] INFO: task apache2:17984 blocked for more than 120 seconds. [1912668.507035] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. : [1912668.555165] apache2 D ffff8101c5637ba0 0 17984 17282 : [1912668.596752] ffff810166a7dd30 0000000000000086 0000000000000000 ffff810166a7dcd8 : [1912668.643341] ffff8101c563c880 ffff81024505f000 0000000000000002 ffff810166a7dd68 : [1912668.699566] 0000000000000086 00000000000cb1a0 0000000000000000 ffff81017f344d60 : [1912668.744773] Call Trace: : [1912668.761754] [<ffffffff8022a3ed>] pick_next_task_fair+0x6e/0x7a : [1912668.829311] [<ffffffff802be0e2>] bio_alloc_bioset+0x89/0xd9 : [1912668.861930] [<ffffffff8024ac3a>] getnstimeofday+0x39/0x98 : [1912668.897005] [<ffffffff802710f6>] sync_page+0x0/0x41 : [1912668.927868] [<ffffffff80429487>] io_schedule+0x5c/0x9e : [1912668.960286] [<ffffffff80271132>] sync_page+0x3c/0x41 : [1912668.991756] [<ffffffff804295fa>] __wait_on_bit_lock+0x36/0x66 : [1912669.031757] [<ffffffff802710e3>] __lock_page+0x5e/0x64 : [1912669.064191] [<ffffffff802461d3>] wake_bit_function+0x0/0x23 : [1912669.100100] [<ffffffff80281bc5>] handle_mm_fault+0x5e4/0x8de : [1912669.134531] [<ffffffff802461a5>] autoremove_wake_function+0x0/0x2e : [1912669.174623] [<ffffffff802aa108>] fcntl_setlk+0x1cf/0x291 : [1912669.210623] [<ffffffff802461a5>] autoremove_wake_function+0x0/0x2e : [1912669.246923] [<ffffffff802a677f>] sys_fcntl+0x280/0x2f7 After googling for "mutex_lock_slowpath" I can only find the Kernel mailing list discussions that this issue was introduced in some commit. Wthout reference to verison. Discussions as recent as Jan 25, 2011. The Kernel I am using is form Debian Lenny, year ago. What should I do? Is this bug even fixed in kernel? if it's such obvious bug why it happens so rarely? Should I download latest kernel from kernel.org and upgrade? Should I use Debian backports to install new "Approved" kernel? Am I missing something? What to do?

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• Clean Code Development & Flexible work environment - MSCC 26.10.2013

  Finally, some spare time to summarize my impressions and experiences of the recent meetup of Mauritius Software Craftsmanship Community. I already posted my comment on the event and on our social media networks: Professional - It's getting better with our meetups and I really appreciated that 'seniors' and 'juniors' were present today. Despite running a little bit out of time it was really great to see more students coming to the gathering. This time we changed location for our Saturday meetup and it worked out very well. A big thank you to Ebene Accelerator, namely Mrs Poonum, for the ability to use their meeting rooms for our community get-together. Already some weeks ago I had a very pleasant conversation with her about the MSCC aims, 'mission' and how we organise things. Additionally, I think that an environment like the Ebene Accelerator is a good choice as it acts as an incubator for young developers and start-ups. Reactions from other craftsmen Before I put my thoughts about our recent meeting down, I'd like to mention and cross-link to some of the other craftsmen that were present: "MSCC meet up is a massive knowledge gaining strategies for students, future entrepreneurs, or for geeks all around. Knowledge sharing becomes a fun. For those who have not been able to made it do subscribe on our MSCC meet up group at meetup.com." -- Nitin on Learning is fun with #MSCC #Ebene Accelerator "We then talked about the IT industry in Mauritius, salary issues in various field like system administration, software development etc. We analysed the reasons why people tend to hop from one company to another. That was a fun debate." -- Ish on MSCC meetup - Gang of Geeks "Flexible Learning Environment was quite interesting since these lines struck cords : "You're not a secretary....9 to 5 shouldn't suit you"....This allowed reflection...deep reflection....especially regarding the local mindset...which should be changed in a way which would promote creativity rather than choking it till death..." -- Yannick on 2nd MSCC Monthly Meet-up And others on Facebook... ;-) Visual impressions are available on our Meetup event page. More first time attendees We great pleasure I noticed that we have once again more first time visitors. A quick overlook showed that we had a majority of UoM students in first, second or last year. Some of them are already participating in the UoM Computer Club or are nominated as members of the Microsoft Student Partner (MSP) programme. Personally, I really appreciate the fact that the MSCC is able to gather such a broad audience. And as I wrote initially, the MSCC is technology-agnostic; we want IT people from any segment of this business. Of course, students which are about to delve into the 'real world' of working are highly welcome, and I hope that they might get one or other glimpse of experience or advice from employees. Sticking to the schedule? No, not really... And honestly, it was a good choice to go a little bit of the beaten tracks. I mean, yes we have a 'rough' agenda of topics that we would like to talk about or having a presentation about. But we keep it 'agile'. Due to the high number of new faces, we initiated another quick round of introductions and I gave a really brief overview of the MSCC. Next, we started to reflect on the Clean Code Developer (CCD) - Red Grade which we introduced on the last meetup. Nirvan was the lucky one and he did a good job on summarizing the various abbreviations of the first level of being a CCD. Actually, more interesting, we exchanged experience about the principles and practices of Red Grade, and it was very informative to get to know that Yann actually 'interviewed' a couple of friends, other students, local guys working in IT companies as well as some IT friends from India in order to counter-check on what he learned first-hand about Clean Code. Currently, he is reading the book of Robert C. Martin on that topic and I'm looking forward to his review soon. More output generates more input What seems to be like a personal mantra is working out pretty well for me since the beginning of this year. Being more active on social media networks, writing more article on my blog, starting the Mauritius Software Craftsmanship Community, and contributing more to other online communities has helped me to receive more project requests, job offers and possibilities to expand my business at IOS Indian Ocean Software Ltd. Actually, it is not a coincidence that one of the questions new craftsmen should answer during registration asks about having a personal blog. Whether you are just curious about IT, right in the middle of your Computer Studies, or already working in software development or system administration since a while you should consider to advertise and market yourself online. Easiest way to resolve this are to have online profiles on professional social media networks like LinkedIn, Xing, Twitter, and Google+ (no Facebook should be considered for private only), and considering to have a personal blog. Why? -- Be yourself, be proud of your work, and let other people know that you're passionate about your profession. Trust me, this is going to open up opportunities you might not have dreamt about... Exchanging ideas about having a professional online presence - MSCC meetup on the 26th October 2013 Furthermore, consider to put your Curriculum Vitae online, too. There are quite a number of service providers like 1ClickCV, Stack Overflow Careers 2.0, etc. which give you the ability to have an up to date CV online. At least put it on your site, next to your personal blog. Similar to what you would be able to see on my site here. Cyber Island Mauritius - are we there? A couple of weeks ago I got a 'cold' message on LinkedIn from someone living in the U.S. asking about the circumstances and conditions of the IT world of Mauritius. He has a great business idea, venture capital and is currently looking for a team of software developers (mainly mobile - iOS) for a new startup here in Mauritius. Since then we exchanged quite some details through private messages and Skype conversations, and I suggested that it might be a good chance to join our meetup through a conference call and see for yourself about potential candidates. During approximately 30 to 40 minutes the brief idea of the new startup was presented - very promising state-of-the-art technology aspects and integration of various public APIs -, and we had a good Q&A session about it. Also thanks to the excellent bandwidth provided by the Ebene Accelerator the video conference between three parties went absolutely well. Clean Code Developer - Orange Grade Hahaha - nice one... Being at the Orange Tower at Ebene and then talking about an Orange Grade as CCD. Well, once again I provided an overview of the principles and practices in that rank of Clean Code, and similar to our last meetup we discussed on the various aspect of each principle, whether someone already got in touch with it during studies or work, and how it could affect their future view on their source code. Following are the principles and practices of Clean Code Developer - Orange Grade: CCD Orange Grade - Principles Single Level of Abstraction (SLA) Single Responsibility Principle (SRP) Separation of Concerns (SoC) Source Code conventions CCD Orange Grade - Practices Issue Tracking Automated Integration Tests Reading, Reading, Reading Reviews Especially the part on reading technical books got some extra attention. We quickly gathered our views on that and came up with a result that ranges between Zero (0) and up to Fifteen (15) book titles per year. Personally, I'm keeping my progress between Six (6) and Eight (8) titles per year, but at least One (1) per quarter of a year. Which is also connected to the fact that I'm participating in the O'Reilly Reader Review Program and have a another benefit to get access to free books only by writing and publishing a review afterwards. We also had a good exchange on the extended topic of 'Reviews' - which to my opinion is abnormal difficult here in Mauritius for various reasons. As far as I can tell from my experience working with Mauritian software developers, either as colleagues, employees or during consulting services there are unfortunately two dominant pattern on that topic: Keeping quiet Running away Honestly, I have no evidence about why these are the two 'solutions' on reviews but that's the situation that I had to face over the last couple of years. Sitting together and talking about problematic issues, tackling down root causes of de-motivational activities and working on general improvements doesn't seem to have a ground within the IT world of Mauritius. Are you a typist or a creative software craftsman? - MSCC meetup on the 26th October 2013 One very good example that we talked about was the fact of 'job hoppers' as you can easily observe it on someone's CV - those people change job every single year; for no obvious reason! Frankly speaking, I wouldn't even consider an IT person like to for an interview. As a company you're investing money and effort into the abilities of your employees. Hiring someone that won't stay for a longer period is out of question. And sorry to say, these kind of IT guys smell fishy about their capabilities and more likely to cause problems than actually produce productive results. One of the reasons why there is a probation period on an employment contract is to give you the liberty to leave as early as possible in case that you don't like your new position. Don't fool yourself or waste other people's time and money by hanging around a full year only to snatch off the bonus payment... Future outlook: Developer's Conference Even though it is not official yet I already mentioned it several times during our weekly Code & Coffee sessions. The MSCC is looking forward to be able to organise or to contribute to an upcoming IT event. Currently, the rough schedule is set for April 2014 but this mainly depends on availability of location(s), a decent time frame for preparations, and the underlying procedures with public bodies to have it approved and so on. As soon as the information about date and location has been fixed there will be a 'Call for Papers' period in order to attract local IT enthusiasts to apply for a session slot and talk about their field of work and their passion in IT. More to come for sure... My resume of the day It was a great gathering and I am very pleased about the fact that we had another 15 craftsmen (plus 2 businessmen on conference call plus 2 young apprentices) in the same room, talking about IT related topics and sharing their experience as employees and students. Personally, I really appreciated the feedback from the students about their current view on their future career, and I really hope that some of them are going to pursue their dreams. Start promoting yourself and it will happen... Looking forward to your blogs! And last but not least our numbers on Meetup and Facebook have been increased as a direct consequence of this meetup. Please, spread the word about the MSCC and get your friends and colleagues to join our official site. The higher the number of craftsmen we have the better chances we have t achieve something great! Thanks!

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• Bridging LXC containers to host eth0 so they can have a public IP

  - by Vianney Stroebel

  UPDATE: I found the solution there: http://www.linuxfoundation.org/collaborate/workgroups/networking/bridge#No_traffic_gets_trough_.28except_ARP_and_STP.29 # cd /proc/sys/net/bridge # ls bridge-nf-call-arptables bridge-nf-call-iptables bridge-nf-call-ip6tables bridge-nf-filter-vlan-tagged # for f in bridge-nf-*; do echo 0 $f; done But I'd like to have expert opinions on this: is it safe to disable all bridge-nf-*? What are they here for? END OF UPDATE I need to bridge LXC containers to the physical interface (eth0) of my host, reading numerous tutorials, documents and blog posts on the subject. I need the containers to have their own public IP (which I've previously done KVM/libvirt). After two days of searching and trying, I still can't make it work with LXC containers. The host runs a freshly installed Ubuntu Server Quantal (12.10) with only libvirt (which I'm not using here) and lxc installed. I created the containers with : lxc-create -t ubuntu -n mycontainer So they also run Ubuntu 12.10. Content of /var/lib/lxc/mycontainer/config is: lxc.utsname = mycontainer lxc.mount = /var/lib/lxc/test/fstab lxc.rootfs = /var/lib/lxc/test/rootfs lxc.network.type = veth lxc.network.flags = up lxc.network.link = br0 lxc.network.name = eth0 lxc.network.veth.pair = vethmycontainer lxc.network.ipv4 = 179.43.46.233 lxc.network.hwaddr= 02:00:00:86:5b:11 lxc.devttydir = lxc lxc.tty = 4 lxc.pts = 1024 lxc.arch = amd64 lxc.cap.drop = sys_module mac_admin mac_override lxc.pivotdir = lxc_putold # uncomment the next line to run the container unconfined: #lxc.aa_profile = unconfined lxc.cgroup.devices.deny = a # Allow any mknod (but not using the node) lxc.cgroup.devices.allow = c *:* m lxc.cgroup.devices.allow = b *:* m # /dev/null and zero lxc.cgroup.devices.allow = c 1:3 rwm lxc.cgroup.devices.allow = c 1:5 rwm # consoles lxc.cgroup.devices.allow = c 5:1 rwm lxc.cgroup.devices.allow = c 5:0 rwm #lxc.cgroup.devices.allow = c 4:0 rwm #lxc.cgroup.devices.allow = c 4:1 rwm # /dev/{,u}random lxc.cgroup.devices.allow = c 1:9 rwm lxc.cgroup.devices.allow = c 1:8 rwm lxc.cgroup.devices.allow = c 136:* rwm lxc.cgroup.devices.allow = c 5:2 rwm # rtc lxc.cgroup.devices.allow = c 254:0 rwm #fuse lxc.cgroup.devices.allow = c 10:229 rwm #tun lxc.cgroup.devices.allow = c 10:200 rwm #full lxc.cgroup.devices.allow = c 1:7 rwm #hpet lxc.cgroup.devices.allow = c 10:228 rwm #kvm lxc.cgroup.devices.allow = c 10:232 rwm Then I changed my host /etc/network/interfaces to: auto lo iface lo inet loopback auto br0 iface br0 inet static bridge_ports eth0 bridge_fd 0 address 92.281.86.226 netmask 255.255.255.0 network 92.281.86.0 broadcast 92.281.86.255 gateway 92.281.86.254 dns-nameservers 213.186.33.99 dns-search ovh.net When I try command line configuration ("brctl addif", "ifconfig eth0", etc.) my remote host becomes inaccessible and I have to hard reboot it. I changed the content of /var/lib/lxc/mycontainer/rootfs/etc/network/interfaces to: auto lo iface lo inet loopback auto eth0 iface eth0 inet static address 179.43.46.233 netmask 255.255.255.255 broadcast 178.33.40.233 gateway 92.281.86.254 It takes several minutes for mycontainer to start (lxc-start -n mycontainer). I tried replacing gateway 92.281.86.254 by : post-up route add 92.281.86.254 dev eth0 post-up route add default gw 92.281.86.254 post-down route del 92.281.86.254 dev eth0 post-down route del default gw 92.281.86.254 My container then starts instantly. But whatever configuration I set in /var/lib/lxc/mycontainer/rootfs/etc/network/interfaces, I cannot ping from mycontainer to any IP (including the host's) : ubuntu@mycontainer:~$ ping 92.281.86.226 PING 92.281.86.226 (92.281.86.226) 56(84) bytes of data. ^C --- 92.281.86.226 ping statistics --- 6 packets transmitted, 0 received, 100% packet loss, time 5031ms And my host cannot ping the container: root@host:~# ping 179.43.46.233 PING 179.43.46.233 (179.43.46.233) 56(84) bytes of data. ^C --- 179.43.46.233 ping statistics --- 5 packets transmitted, 0 received, 100% packet loss, time 4000ms My container's ifconfig: ubuntu@mycontainer:~$ ifconfig eth0 Link encap:Ethernet HWaddr 02:00:00:86:5b:11 inet addr:179.43.46.233 Bcast:255.255.255.255 Mask:0.0.0.0 inet6 addr: fe80::ff:fe79:5a31/64 Scope:Link UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 RX packets:64 errors:0 dropped:6 overruns:0 frame:0 TX packets:54 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1000 RX bytes:4070 (4.0 KB) TX bytes:4168 (4.1 KB) lo Link encap:Local Loopback inet addr:127.0.0.1 Mask:255.0.0.0 inet6 addr: ::1/128 Scope:Host UP LOOPBACK RUNNING MTU:16436 Metric:1 RX packets:32 errors:0 dropped:0 overruns:0 frame:0 TX packets:32 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:0 RX bytes:2496 (2.4 KB) TX bytes:2496 (2.4 KB) My host's ifconfig: root@host:~# ifconfig br0 Link encap:Ethernet HWaddr 4c:72:b9:43:65:2b inet addr:92.281.86.226 Bcast:91.121.67.255 Mask:255.255.255.0 inet6 addr: fe80::4e72:b9ff:fe43:652b/64 Scope:Link UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 RX packets:1453 errors:0 dropped:18 overruns:0 frame:0 TX packets:1630 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:0 RX bytes:145125 (145.1 KB) TX bytes:299943 (299.9 KB) eth0 Link encap:Ethernet HWaddr 4c:72:b9:43:65:2b UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 RX packets:3178 errors:0 dropped:0 overruns:0 frame:0 TX packets:1637 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1000 RX bytes:298263 (298.2 KB) TX bytes:309167 (309.1 KB) Interrupt:20 Memory:fe500000-fe520000 lo Link encap:Local Loopback inet addr:127.0.0.1 Mask:255.0.0.0 inet6 addr: ::1/128 Scope:Host UP LOOPBACK RUNNING MTU:16436 Metric:1 RX packets:6 errors:0 dropped:0 overruns:0 frame:0 TX packets:6 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:0 RX bytes:300 (300.0 B) TX bytes:300 (300.0 B) vethtest Link encap:Ethernet HWaddr fe:0d:7f:3e:70:88 inet6 addr: fe80::fc0d:7fff:fe3e:7088/64 Scope:Link UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 RX packets:54 errors:0 dropped:0 overruns:0 frame:0 TX packets:67 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1000 RX bytes:4168 (4.1 KB) TX bytes:4250 (4.2 KB) virbr0 Link encap:Ethernet HWaddr de:49:c5:66:cf:84 inet addr:192.168.122.1 Bcast:192.168.122.255 Mask:255.255.255.0 UP BROADCAST MULTICAST MTU:1500 Metric:1 RX packets:0 errors:0 dropped:0 overruns:0 frame:0 TX packets:0 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:0 RX bytes:0 (0.0 B) TX bytes:0 (0.0 B) I have disabled lxcbr0 (USE_LXC_BRIDGE="false" in /etc/default/lxc). root@host:~# brctl show bridge name bridge id STP enabled interfaces br0 8000.4c72b943652b no eth0 vethtest I have configured the IP 179.43.46.233 to point to 02:00:00:86:5b:11 in my hosting provider (OVH) config panel. (The IPs in this post are not the real ones.) Thanks for reading this long question! :-) Vianney

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• Inside the DLR – Invoking methods

  - by Simon Cooper

  So, we’ve looked at how a dynamic call is represented in a compiled assembly, and how the dynamic lookup is performed at runtime. The last piece of the puzzle is how the resolved method gets invoked, and that is the subject of this post. Invoking methods As discussed in my previous posts, doing a full lookup and bind at runtime each and every single time the callsite gets invoked would be far too slow to be usable. The results obtained from the callsite binder must to be cached, along with a series of conditions to determine whether the cached result can be reused. So, firstly, how are the conditions represented? These conditions can be anything; they are determined entirely by the semantics of the language the binder is representing. The binder has to be able to return arbitary code that is then executed to determine whether the conditions apply or not. Fortunately, .NET 4 has a neat way of representing arbitary code that can be easily combined with other code – expression trees. All the callsite binder has to return is an expression (called a ‘restriction’) that evaluates to a boolean, returning true when the restriction passes (indicating the corresponding method invocation can be used) and false when it does’t. If the bind result is also represented in an expression tree, these can be combined easily like so: if ([restriction is true]) { [invoke cached method] } Take my example from my previous post: public class ClassA { public static void TestDynamic() { CallDynamic(new ClassA(), 10); CallDynamic(new ClassA(), "foo"); } public static void CallDynamic(dynamic d, object o) { d.Method(o); } public void Method(int i) {} public void Method(string s) {} } When the Method(int) method is first bound, along with an expression representing the result of the bind lookup, the C# binder will return the restrictions under which that bind can be reused. In this case, it can be reused if the types of the parameters are the same: if (thisArg.GetType() == typeof(ClassA) && arg1.GetType() == typeof(int)) { thisClassA.Method(i); } Caching callsite results So, now, it’s up to the callsite to link these expressions returned from the binder together in such a way that it can determine which one from the many it has cached it should use. This caching logic is all located in the System.Dynamic.UpdateDelegates class. It’ll help if you’ve got this type open in a decompiler to have a look yourself. For each callsite, there are 3 layers of caching involved: The last method invoked on the callsite. All methods that have ever been invoked on the callsite. All methods that have ever been invoked on any callsite of the same type. We’ll cover each of these layers in order Level 1 cache: the last method called on the callsite When a CallSite<T> object is first instantiated, the Target delegate field (containing the delegate that is called when the callsite is invoked) is set to one of the UpdateAndExecute generic methods in UpdateDelegates, corresponding to the number of parameters to the callsite, and the existance of any return value. These methods contain most of the caching, invoke, and binding logic for the callsite. The first time this method is invoked, the UpdateAndExecute method finds there aren’t any entries in the caches to reuse, and invokes the binder to resolve a new method. Once the callsite has the result from the binder, along with any restrictions, it stitches some extra expressions in, and replaces the Target field in the callsite with a compiled expression tree similar to this (in this example I’m assuming there’s no return value): if ([restriction is true]) { [invoke cached method] return; } if (callSite._match) { _match = false; return; } else { UpdateAndExecute(callSite, arg0, arg1, ...); } Woah. What’s going on here? Well, this resulting expression tree is actually the first level of caching. The Target field in the callsite, which contains the delegate to call when the callsite is invoked, is set to the above code compiled from the expression tree into IL, and then into native code by the JIT. This code checks whether the restrictions of the last method that was invoked on the callsite (the ‘primary’ method) match, and if so, executes that method straight away. This means that, the next time the callsite is invoked, the first code that executes is the restriction check, executing as native code! This makes this restriction check on the primary cached delegate very fast. But what if the restrictions don’t match? In that case, the second part of the stitched expression tree is executed. What this section should be doing is calling back into the UpdateAndExecute method again to resolve a new method. But it’s slightly more complicated than that. To understand why, we need to understand the second and third level caches. Level 2 cache: all methods that have ever been invoked on the callsite When a binder has returned the result of a lookup, as well as updating the Target field with a compiled expression tree, stitched together as above, the callsite puts the same compiled expression tree in an internal list of delegates, called the rules list. This list acts as the level 2 cache. Why use the same delegate? Stitching together expression trees is an expensive operation. You don’t want to do it every time the callsite is invoked. Ideally, you would create one expression tree from the binder’s result, compile it, and then use the resulting delegate everywhere in the callsite. But, if the same delegate is used to invoke the callsite in the first place, and in the caches, that means each delegate needs two modes of operation. An ‘invoke’ mode, for when the delegate is set as the value of the Target field, and a ‘match’ mode, used when UpdateAndExecute is searching for a method in the callsite’s cache. Only in the invoke mode would the delegate call back into UpdateAndExecute. In match mode, it would simply return without doing anything. This mode is controlled by the _match field in CallSite<T>. The first time the callsite is invoked, _match is false, and so the Target delegate is called in invoke mode. Then, if the initial restriction check fails, the Target delegate calls back into UpdateAndExecute. This method sets _match to true, then calls all the cached delegates in the rules list in match mode to try and find one that passes its restrictions, and invokes it. However, there needs to be some way for each cached delegate to inform UpdateAndExecute whether it passed its restrictions or not. To do this, as you can see above, it simply re-uses _match, and sets it to false if it did not pass the restrictions. This allows the code within each UpdateAndExecute method to check for cache matches like so: foreach (T cachedDelegate in Rules) { callSite._match = true; cachedDelegate(); // sets _match to false if restrictions do not pass if (callSite._match) { // passed restrictions, and the cached method was invoked // set this delegate as the primary target to invoke next time callSite.Target = cachedDelegate; return; } // no luck, try the next one... } Level 3 cache: all methods that have ever been invoked on any callsite with the same signature The reason for this cache should be clear – if a method has been invoked through a callsite in one place, then it is likely to be invoked on other callsites in the codebase with the same signature. Rather than living in the callsite, the ‘global’ cache for callsite delegates lives in the CallSiteBinder class, in the Cache field. This is a dictionary, typed on the callsite delegate signature, providing a RuleCache<T> instance for each delegate signature. This is accessed in the same way as the level 2 callsite cache, by the UpdateAndExecute methods. When a method is matched in the global cache, it is copied into the callsite and Target cache before being executed. Putting it all together So, how does this all fit together? Like so (I’ve omitted some implementation & performance details): That, in essence, is how the DLR performs its dynamic calls nearly as fast as statically compiled IL code. Extensive use of expression trees, compiled to IL and then into native code. Multiple levels of caching, the first of which executes immediately when the dynamic callsite is invoked. And a clever re-use of compiled expression trees that can be used in completely different contexts without being recompiled. All in all, a very fast and very clever reflection caching mechanism.

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• XNA shield effect with a Primative sphere problem

  - by Sparky41

  I'm having issue with a shield effect i'm trying to develop. I want to do a shield effect that surrounds part of a model like this: http://i.imgur.com/jPvrf.png I currently got this: http://i.imgur.com/Jdin7.png (The red likes are a simple texture a black background with a red cross in it, for testing purposes: http://i.imgur.com/ODtzk.png where the smaller cross in the middle shows the contact point) This sphere is drawn via a primitive (DrawIndexedPrimitives) This is how i calculate the pieces of the sphere using a class i've called Sphere (this class is based off the code here: http://xbox.create.msdn.com/en-US/education/catalog/sample/primitives_3d) public class Sphere { // During the process of constructing a primitive model, vertex // and index data is stored on the CPU in these managed lists. List vertices = new List(); List indices = new List(); // Once all the geometry has been specified, the InitializePrimitive // method copies the vertex and index data into these buffers, which // store it on the GPU ready for efficient rendering. VertexBuffer vertexBuffer; IndexBuffer indexBuffer; BasicEffect basicEffect; public Vector3 position = Vector3.Zero; public Matrix RotationMatrix = Matrix.Identity; public Texture2D texture; /// <summary> /// Constructs a new sphere primitive, /// with the specified size and tessellation level. /// </summary> public Sphere(float diameter, int tessellation, Texture2D text, float up, float down, float portstar, float frontback) { texture = text; if (tessellation < 3) throw new ArgumentOutOfRangeException("tessellation"); int verticalSegments = tessellation; int horizontalSegments = tessellation * 2; float radius = diameter / 2; // Start with a single vertex at the bottom of the sphere. AddVertex(Vector3.Down * ((radius / up) + 1), Vector3.Down, Vector2.Zero);//bottom position5 // Create rings of vertices at progressively higher latitudes. for (int i = 0; i < verticalSegments - 1; i++) { float latitude = ((i + 1) * MathHelper.Pi / verticalSegments) - MathHelper.PiOver2; float dy = (float)Math.Sin(latitude / up);//(up)5 float dxz = (float)Math.Cos(latitude); // Create a single ring of vertices at this latitude. for (int j = 0; j < horizontalSegments; j++) { float longitude = j * MathHelper.TwoPi / horizontalSegments; float dx = (float)(Math.Cos(longitude) * dxz) / portstar;//port and starboard (right)2 float dz = (float)(Math.Sin(longitude) * dxz) * frontback;//front and back1.4 Vector3 normal = new Vector3(dx, dy, dz); AddVertex(normal * radius, normal, new Vector2(j, i)); } } // Finish with a single vertex at the top of the sphere. AddVertex(Vector3.Up * ((radius / down) + 1), Vector3.Up, Vector2.One);//top position5 // Create a fan connecting the bottom vertex to the bottom latitude ring. for (int i = 0; i < horizontalSegments; i++) { AddIndex(0); AddIndex(1 + (i + 1) % horizontalSegments); AddIndex(1 + i); } // Fill the sphere body with triangles joining each pair of latitude rings. for (int i = 0; i < verticalSegments - 2; i++) { for (int j = 0; j < horizontalSegments; j++) { int nextI = i + 1; int nextJ = (j + 1) % horizontalSegments; AddIndex(1 + i * horizontalSegments + j); AddIndex(1 + i * horizontalSegments + nextJ); AddIndex(1 + nextI * horizontalSegments + j); AddIndex(1 + i * horizontalSegments + nextJ); AddIndex(1 + nextI * horizontalSegments + nextJ); AddIndex(1 + nextI * horizontalSegments + j); } } // Create a fan connecting the top vertex to the top latitude ring. for (int i = 0; i < horizontalSegments; i++) { AddIndex(CurrentVertex - 1); AddIndex(CurrentVertex - 2 - (i + 1) % horizontalSegments); AddIndex(CurrentVertex - 2 - i); } //InitializePrimitive(graphicsDevice); } /// <summary> /// Adds a new vertex to the primitive model. This should only be called /// during the initialization process, before InitializePrimitive. /// </summary> protected void AddVertex(Vector3 position, Vector3 normal, Vector2 texturecoordinate) { vertices.Add(new VertexPositionNormal(position, normal, texturecoordinate)); } /// <summary> /// Adds a new index to the primitive model. This should only be called /// during the initialization process, before InitializePrimitive. /// </summary> protected void AddIndex(int index) { if (index > ushort.MaxValue) throw new ArgumentOutOfRangeException("index"); indices.Add((ushort)index); } /// <summary> /// Queries the index of the current vertex. This starts at /// zero, and increments every time AddVertex is called. /// </summary> protected int CurrentVertex { get { return vertices.Count; } } public void InitializePrimitive(GraphicsDevice graphicsDevice) { // Create a vertex declaration, describing the format of our vertex data. // Create a vertex buffer, and copy our vertex data into it. vertexBuffer = new VertexBuffer(graphicsDevice, typeof(VertexPositionNormal), vertices.Count, BufferUsage.None); vertexBuffer.SetData(vertices.ToArray()); // Create an index buffer, and copy our index data into it. indexBuffer = new IndexBuffer(graphicsDevice, typeof(ushort), indices.Count, BufferUsage.None); indexBuffer.SetData(indices.ToArray()); // Create a BasicEffect, which will be used to render the primitive. basicEffect = new BasicEffect(graphicsDevice); //basicEffect.EnableDefaultLighting(); } /// <summary> /// Draws the primitive model, using the specified effect. Unlike the other /// Draw overload where you just specify the world/view/projection matrices /// and color, this method does not set any renderstates, so you must make /// sure all states are set to sensible values before you call it. /// </summary> public void Draw(Effect effect) { GraphicsDevice graphicsDevice = effect.GraphicsDevice; // Set our vertex declaration, vertex buffer, and index buffer. graphicsDevice.SetVertexBuffer(vertexBuffer); graphicsDevice.Indices = indexBuffer; graphicsDevice.BlendState = BlendState.Additive; foreach (EffectPass effectPass in effect.CurrentTechnique.Passes) { effectPass.Apply(); int primitiveCount = indices.Count / 3; graphicsDevice.DrawIndexedPrimitives(PrimitiveType.TriangleList, 0, 0, vertices.Count, 0, primitiveCount); } graphicsDevice.BlendState = BlendState.Opaque; } /// <summary> /// Draws the primitive model, using a BasicEffect shader with default /// lighting. Unlike the other Draw overload where you specify a custom /// effect, this method sets important renderstates to sensible values /// for 3D model rendering, so you do not need to set these states before /// you call it. /// </summary> public void Draw(Camera camera, Color color) { // Set BasicEffect parameters. basicEffect.World = GetWorld(); basicEffect.View = camera.view; basicEffect.Projection = camera.projection; basicEffect.DiffuseColor = color.ToVector3(); basicEffect.TextureEnabled = true; basicEffect.Texture = texture; GraphicsDevice device = basicEffect.GraphicsDevice; device.DepthStencilState = DepthStencilState.Default; if (color.A < 255) { // Set renderstates for alpha blended rendering. device.BlendState = BlendState.AlphaBlend; } else { // Set renderstates for opaque rendering. device.BlendState = BlendState.Opaque; } // Draw the model, using BasicEffect. Draw(basicEffect); } public virtual Matrix GetWorld() { return /*world */ Matrix.CreateScale(1f) * RotationMatrix * Matrix.CreateTranslation(position); } } public struct VertexPositionNormal : IVertexType { public Vector3 Position; public Vector3 Normal; public Vector2 TextureCoordinate; /// <summary> /// Constructor. /// </summary> public VertexPositionNormal(Vector3 position, Vector3 normal, Vector2 textCoor) { Position = position; Normal = normal; TextureCoordinate = textCoor; } /// <summary> /// A VertexDeclaration object, which contains information about the vertex /// elements contained within this struct. /// </summary> public static readonly VertexDeclaration VertexDeclaration = new VertexDeclaration ( new VertexElement(0, VertexElementFormat.Vector3, VertexElementUsage.Position, 0), new VertexElement(12, VertexElementFormat.Vector3, VertexElementUsage.Normal, 0), new VertexElement(24, VertexElementFormat.Vector2, VertexElementUsage.TextureCoordinate, 0) ); VertexDeclaration IVertexType.VertexDeclaration { get { return VertexPositionNormal.VertexDeclaration; } } } A simple call to the class to initialise it. The Draw method is called in the master draw method in the Gamecomponent. My current thoughts on this are: The direction of the weapon hitting the ship is used to get the middle position for the texture Wrap a texture around the drawn sphere based on this point of contact Problem is i'm not sure how to do this. Can anyone help or if you have a better idea please tell me i'm open for opinion? :-) Thanks.

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• UpdatePanel, JavaScript postback and changing querystring at same time in SharePoint Search Page

  - by Lee Dale

  Hi Guys, Been tearing my hear out with this one. Let me see if I can explain: I have a SharePoint results page on which I have a Search Results Core WebPart. Now I want to change the parameter in the querystring when I postback the page so that the WebPart returns different results for each parameter e.g. the querystring will be interactivemap.aspx?k=Country:Romania this will filter the results for Romania. First issue is I want to do this with javascript so I call: document.getElementById('aspnetForm').action = "interactivemap.aspx?k=Country:" + country; Nothing special here but the reason I need to call from Javascript is there is also a flash applet on this page from which the Javascript calls originate. When the javascript calls are made the page needs to PostBack but not reload the flash applet. I turned to ASP.Net AJAX for this so I wrapped the search results webpart in an update panel. Now if I use a button within the UpdatePanel to postback the UpdatePanel behaves as expected and does a partial render of the search results webpart not reloading the flash applet. Problem comes because I need postback the page from javscript. I called __doPostBack() as I have used this successully in the past. It works on it's own but fails when I first call the above Javascript before the __doPostBack() (I also tried calling click() on a hidden button) the code for the page is at the bottom. I think the problem comes with the scriptmanager not allowing a partial render when the form post action has changed. My questions are. A) Is there some other way to change the search results webpart parameter without using the querystring. or B) Is there a way around changing the querystring when doing an AJAX postback and getting a partial render. <asp:Content ContentPlaceHolderID="PlaceHolderFullContent" runat="server"> function update(country) { //__doPostBack('ContentUpdatePanel', ''); //document.getElementById('aspnetForm').action = "interactivemap.aspx?k=ArticleCountry:" + country; document.getElementById('ctl00_PlaceHolderFullContent_UpdateButton').click(); } Romania <div class="firstDataTitle"> <div class="datatabletitleOuterWrapper"> <div class="datatabletitle"> <span>Content</span></div> </div> <div class="datatableWrapper"> <div class="dataHolderWrapper"> <div class="datatable"> <div> <div class="searchMain"> <div class="searchZoneMain"> <asp:UpdatePanel runat="server" id="ContentUpdatePanel" UpdateMode="Conditional"> <ContentTemplate> <WebPartPages:webpartzone runat="server" AllowPersonalization="false" title="<%$Resources:sps,LayoutPageZone_BottomZone%>" id="BottomZone" orientation="Vertical" QuickAdd-GroupNames="Search" QuickAdd-ShowListsAndLibraries="false"><ZoneTemplate></ZoneTemplate></WebPartPages:webpartzone> <asp:Button id="UpdateButton" name="UpdateButton" runat="server" Text="Update"/> </ContentTemplate> </asp:UpdatePanel> </div> </div> </div> </div> </div> </div>

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• WPF DataContext does not refresh the DataGrid using MVVM model

  - by vikram bhatia

  Project Overview I have a view which binds to a viewmodel containing 2 ObserverableCollection. The viewmodel constructor populates the first ObserverableCollection and the view datacontext is collected to bind to it through a public property called Sites. Later the 2ed ObserverableCollection is populated in the LoadOrders method and the public property LoadFraudResults is updated for binding it with datacontext. I am using WCF to pull the data from the database and its getting pulled very nicely. VIEWMODEL SOURCE class ManageFraudOrderViewModel:ViewModelBase { #region Fields private readonly ICollectionView collectionViewSites; private readonly ICollectionView collectionView; private ObservableCollection<GeneralAdminService.Website> _sites; private ObservableCollection<FraudService.OrderQueue> _LoadFraudResults; #endregion #region Properties public ObservableCollection<GeneralAdminService.Website> Sites { get { return this._sites; } } public ObservableCollection<FraudService.OrderQueue> LoadFraudResults { get { return this._LoadFraudResults;} } #endregion public ManageFraudOrderViewModel() { //Get values from wfc service model GeneralAdminService.GeneralAdminServiceClient generalAdminServiceClient = new GeneralAdminServiceClient(); GeneralAdminService.Website[] websites = generalAdminServiceClient.GetWebsites(); //Get values from wfc service model if (websites.Length > 0) { _sites = new ObservableCollection<Wqn.Administration.UI.GeneralAdminService.Website>(); foreach (GeneralAdminService.Website website in websites) { _sites.Add((Wqn.Administration.UI.GeneralAdminService.Website)website); } this.collectionViewSites= CollectionViewSource.GetDefaultView(this._sites); } generalAdminServiceClient.Close(); } public void LoadOrders(Wqn.Administration.UI.FraudService.Website website) { //Get values from wfc service model FraudServiceClient fraudServiceClient = new FraudServiceClient(); FraudService.OrderQueue[] OrderQueue = fraudServiceClient.GetFraudOrders(website); //Get values from wfc service model if (OrderQueue.Length > 0) { _LoadFraudResults = new ObservableCollection<Wqn.Administration.UI.FraudService.OrderQueue>(); foreach (FraudService.OrderQueue orderQueue in OrderQueue) { _LoadFraudResults.Add(orderQueue); } } this.collectionViewSites= CollectionViewSource.GetDefaultView(this._LoadFraudResults); fraudServiceClient.Close(); } } VIEW SOURCE public partial class OrderQueueControl : UserControl { private ManageFraudOrderViewModel manageFraudOrderViewModel ; private OrderQueue orderQueue; private ButtonAction ButtonAction; private DispatcherTimer dispatcherTimer; public OrderQueueControl() { LoadOrderQueueForm(); } #region LoadOrderQueueForm private void LoadOrderQueueForm() { //for binding the first observablecollection manageFraudOrderViewModel = new ManageFraudOrderViewModel(); this.DataContext = manageFraudOrderViewModel; } #endregion private void cmbWebsite_SelectionChanged(object sender, SelectionChangedEventArgs e) { BindItemsSource(); } #region BindItemsSource private void BindItemsSource() { using (OverrideCursor cursor = new OverrideCursor(Cursors.Wait)) { if (!string.IsNullOrEmpty(Convert.ToString(cmbWebsite.SelectedItem))) { Wqn.Administration.UI.FraudService.Website website = (Wqn.Administration.UI.FraudService.Website)Enum.Parse(typeof(Wqn.Administration.UI.FraudService.Website),cmbWebsite.SelectedItem.ToString()); //for binding the second observablecollection******* manageFraudOrderViewModel.LoadOrders(website); this.DataContext = manageFraudOrderViewModel; //for binding the second observablecollection******* } } } #endregion } XAML ComboBox x:Name="cmbWebsite" ItemsSource="{Binding Sites}" Margin="5" Width="100" Height="25" SelectionChanged="cmbWebsite_SelectionChanged" DataGrid ItemsSource ={Binding Path = LoadFraudResults} PROBLEM AREA: When I call the LoadOrderQueueForm to bind the first observablecollection and later BindItemsSource to bind 2ed observable collection, everything works fine and no problem for the first time binding. But, when I call BindItemsSource again to repopulate the obseravablecollection based on changed selected combo value via cmbWebsite_SelectionChanged, the observalblecollection gets populated with new value and LoadFraudResults property in viewmodule is populated with new values; but when i call the datacontext to rebind the datagrid,the datagrid does not reflect the changed values. In other words the datagrid doesnot get changed when the datacontext is called the 2ed time in BindItemsSource method of the view. manageFraudOrderViewModel.LoadOrders(website); this.DataContext = manageFraudOrderViewModel; manageFraudOrderViewModel values are correct but the datagrid is not relected with changed values. Please help as I am stuck with this thing for past 2 days and the deadline is approaching near. Thanks in advance

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• Delphi - WndProc() in thread never called

  - by Robert Oschler

  I had code that worked fine when running in the context of the main VCL thread. This code allocated it's own WndProc() in order to handle SendMessage() calls. I am now trying to move it to a background thread because I am concerned that the SendMessage() traffic is affecting the main VCL thread adversely. So I created a worker thread with the sole purpose of allocating the WndProc() in its thread Execute() method to ensure that the WndProc() existed in the thread's execution context. The WndProc() handles the SendMessage() calls as they come in. The problem is that the worker thread's WndProc() method is never triggered. Note, doExecute() is part of a template method that is called by my TThreadExtended class which is a descendant of Delphi's TThread. TThreadExtended implements the thread Execute() method and calls doExecute() in a loop. I triple-checked and doExecute() is being called repeatedly. Also note that I call PeekMessage() right after I create the WndProc() in order to make sure that Windows creates a message queue for the thread. However something I am doing is wrong since the WndProc() method is never triggered. Here's the code below: // ========= BEGIN: CLASS - TWorkerThread ======================== constructor TWorkerThread.Create; begin FWndProcHandle := 0; inherited Create(false); end; // --------------------------------------------------------------- // This call is the thread's Execute() method. procedure TWorkerThread.doExecute; var Msg: TMsg; begin // Create the WndProc() in our thread's context. if FWndProcHandle = 0 then begin FWndProcHandle := AllocateHWND(WndProc); // Call PeekMessage() to make sure we have a window queue. PeekMessage(Msg, FWndProcHandle, 0, 0, PM_NOREMOVE); end; if Self.Terminated then begin // Get rid of the WndProc(). myDeallocateHWnd(FWndProcHandle); end; // Sleep a bit to avoid hogging the CPU. Sleep(5); end; // --------------------------------------------------------------- procedure TWorkerThread.WndProc(Var Msg: TMessage); begin // THIS CODE IS NEVER CALLED. try if Msg.Msg = WM_COPYDATA then begin // Is LParam assigned? if (Msg.LParam > 0) then begin // Yes. Treat it as a copy data structure. with PCopyDataStruct(Msg.LParam)^ do begin ... // Here is where I do my work. end; end; // if Assigned(Msg.LParam) then end; // if Msg.Msg = WM_COPYDATA then finally Msg.Result := 1; end; // try() end; // --------------------------------------------------------------- procedure TWorkerThread.myDeallocateHWnd(Wnd: HWND); var Instance: Pointer; begin Instance := Pointer(GetWindowLong(Wnd, GWL_WNDPROC)); if Instance <> @DefWindowProc then begin // Restore the default windows procedure before freeing memory. SetWindowLong(Wnd, GWL_WNDPROC, Longint(@DefWindowProc)); FreeObjectInstance(Instance); end; DestroyWindow(Wnd); end; // --------------------------------------------------------------- // ========= END : CLASS - TWorkerThread ======================== Thanks, Robert

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• System.AccessViolationException when calling DLL from WCF on IIS.

  - by Wodzu

  Hi guys. I've created just a test WCF service in which I need to call an external DLL. Everything works fine under Visutal Studio development server. However, when I try to use my service on IIS I am getting this error: Exception: System.AccessViolationException Message: Attempted to read or write protected memory. This is often an indication that other memory is corrupt. The stack trace leeds to the call of DLL which is presented below. After a lot of reading and experimenting I am almost sure that the error is caused by wrong passing strings to the called function. Here is how the wrapper for DLL looks like: using System; using System.Runtime.InteropServices; using System.Text; using System; using System.Security; using System.Security.Permissions; using System.Runtime.InteropServices; namespace cdn_api_wodzu { public class cdn_api_wodzu { [DllImport("cdn_api.dll", CharSet=CharSet.Ansi)] // [SecurityPermission(SecurityAction.Assert, Unrestricted = true)] public static extern int XLLogin([In, Out] XLLoginInfo _lLoginInfo, ref int _lSesjaID); } [Serializable, StructLayout(LayoutKind.Sequential)] public class XLLoginInfo { public int Wersja; public int UtworzWlasnaSesje; public int Winieta; public int TrybWsadowy; [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 0x29)] public string ProgramID; [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 0x15)] public string Baza; [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 9)] public string OpeIdent; [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 9)] public string OpeHaslo; [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 200)] public string PlikLog; [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 0x65)] public string SerwerKlucza; public XLLoginInfo() { } } } this is how I call the DLL function: int ErrorID = 0; int SessionID = 0; XLLoginInfo Login; Login = new XLLoginInfo(); Login.Wersja = 18; Login.UtworzWlasnaSesje = 1; Login.Winieta = -1; Login.TrybWsadowy = 1; Login.ProgramID = "TestProgram"; Login.Baza = "TestBase"; Login.OpeIdent = "TestUser"; Login.OpeHaslo = "TestPassword"; Login.PlikLog = "C:\\LogFile.txt"; Login.SerwerKlucza = "MyServ\\MyInstance"; ErrorID = cdn_api_wodzu.cdn_api_wodzu.XLLogin(Login, ref SessionID); When I comment all the string field assigments the function works - it returns me an error message that the program ID has not been given. But when I try to assign a ProgramID (or any other string fields, or all at once) then I am getting the mentioned exception. I am using VS2008 SP.1, WinXP and IIS 5.1. Maybe the ISS itself is a problem? I've tried all the workarounds that has been described here: http://forums.asp.net/t/675515.aspx Thansk for your time. After edit: Installing Windows 2003 Server and IIS 6.0 solved the problem.

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• How to populate a core data store programmatically?

  - by jdmuys

  I have ran out of hairs to pull with a crash in this routine that populates a core data store from a 9000+ line plist file. The crash happened at the very end of the routine inside the call to [managedObjectContext save:&error]. While if I save after every object insertion, the crash doesn't happen. Of course, saving after every object insertion totally kills the performance (from less than a second to many minutes). I modified my code so that it saves every K insertions, and the crash happens as soon as K = 2. The crash is an out-of-bound exception for an NSArray: Serious application error. Exception was caught during Core Data change processing: *** -[NSCFArray objectAtIndex:]: index (1) beyond bounds (1) with userInfo (null) Also maybe relevant, when the exception happen, my fetch result controller controllerDidChangeContent: delegate routine is in the call stack. It simply calls my table view endUpdate routine. I am now running out of ideas. How am I supposed to populate a core data store with a table view? Here is the call stack: #0 0x901ca4e6 in objc_exception_throw #1 0x01d86c3b in +[NSException raise:format:arguments:] #2 0x01d86b9a in +[NSException raise:format:] #3 0x00072cb9 in _NSArrayRaiseBoundException #4 0x00010217 in -[NSCFArray objectAtIndex:] #5 0x002eaaa7 in -[UITableView(_UITableViewPrivate) _endCellAnimationsWithContext:] #6 0x002def02 in -[UITableView endUpdates] #7 0x00004863 in -[AirportViewController controllerDidChangeContent:] at AirportViewController.m:463 #8 0x01c43be1 in -[NSFetchedResultsController(PrivateMethods) _managedObjectContextDidChange:] #9 0x0001462a in _nsnote_callback #10 0x01d31005 in _CFXNotificationPostNotification #11 0x00011ee0 in -[NSNotificationCenter postNotificationName:object:userInfo:] #12 0x01ba417d in -[NSManagedObjectContext(_NSInternalNotificationHandling) _postObjectsDidChangeNotificationWithUserInfo:] #13 0x01c03763 in -[NSManagedObjectContext(_NSInternalChangeProcessing) _createAndPostChangeNotification:withDeletions:withUpdates:withRefreshes:] #14 0x01b885ea in -[NSManagedObjectContext(_NSInternalChangeProcessing) _processRecentChanges:] #15 0x01bbe728 in -[NSManagedObjectContext save:] #16 0x000039ea in -[AirportViewController populateAirports] at AirportViewController.m:112 Here is the code to the routine. I apologize because a number of lines are probably irrelevant, but I'd rather err on that side. The crash happens the very first time it calls [managedObjectContext save:&error]: - (void) populateAirports { NSBundle *meBundle = [NSBundle mainBundle]; NSString *dbPath = [meBundle pathForResource:@"DuckAirportsBin" ofType:@"plist"]; NSArray *initialAirports = [[NSArray alloc] initWithContentsOfFile:dbPath]; //********************************************************************************* // get existing countries NSMutableDictionary *countries = [[NSMutableDictionary alloc] initWithCapacity:200]; NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] init]; NSEntityDescription *entity = [NSEntityDescription entityForName:@"Country" inManagedObjectContext:managedObjectContext]; [fetchRequest setEntity:entity]; NSError *error = nil; NSArray *values = [managedObjectContext executeFetchRequest:fetchRequest error:&error]; if (!values) { NSLog(@"Unresolved error %@, %@", error, [error userInfo]); abort(); } int numCountries = [values count]; NSLog(@"We have %d countries in store", numCountries); for (Country *aCountry in values) { [countries setObject:aCountry forKey:aCountry.code]; } [fetchRequest release]; //********************************************************************************* // read airports int numAirports = 0; int numUnsavedAirports = 0; #define MAX_UNSAVED_AIRPORTS_BEFORE_SAVE 2 numCountries = 0; for (NSDictionary *anAirport in initialAirports) { NSAutoreleasePool * pool = [[NSAutoreleasePool alloc] init]; NSString *countryCode = [anAirport objectForKey:@"country"]; Country *thatCountry = [countries objectForKey:countryCode]; if (!thatCountry) { thatCountry = [NSEntityDescription insertNewObjectForEntityForName:@"Country" inManagedObjectContext:managedObjectContext]; thatCountry.code = countryCode; thatCountry.name = [anAirport objectForKey:@"country_name"]; thatCountry.population = 0; [countries setObject:thatCountry forKey:countryCode]; numCountries++; NSLog(@"Found %dth country %@=%@", numCountries, countryCode, thatCountry.name); } // now that we have the country, we create the airport Airport *newAirport = [NSEntityDescription insertNewObjectForEntityForName:@"Airport" inManagedObjectContext:managedObjectContext]; newAirport.city = [anAirport objectForKey:@"city"]; newAirport.code = [anAirport objectForKey:@"code"]; newAirport.name = [anAirport objectForKey:@"name"]; newAirport.country_name = [anAirport objectForKey:@"country_name"]; newAirport.latitude = [NSNumber numberWithDouble:[[anAirport objectForKey:@"latitude"] doubleValue]]; newAirport.longitude = [NSNumber numberWithDouble:[[anAirport objectForKey:@"longitude"] doubleValue]]; newAirport.altitude = [NSNumber numberWithDouble:[[anAirport objectForKey:@"altitude"] doubleValue]]; newAirport.country = thatCountry; // [thatCountry addAirportsObject:newAirport]; numAirports++; numUnsavedAirports++; if (numUnsavedAirports >= MAX_UNSAVED_AIRPORTS_BEFORE_SAVE) { if (![managedObjectContext save:&error]) { NSLog(@"Unresolved error %@, %@", error, [error userInfo]); abort(); } numUnsavedAirports = 0; } [pool release]; }

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• How can I dynamically change auto complete entries in a C# combobox or textbox?

  - by Sam Hopkins

  I have a combobox in C# and I want to use auto complete suggestions with it, however I want to be able to change the auto complete entries as the user types, because the possible valid entries are far too numerous to populate the AutoCompleteStringCollection at startup. As an example, suppose I'm letting the user type in a name. I have a list of possible first names ("Joe", "John") and a list of surnames ("Bloggs", "Smith"), but if I have a thousand of each, then that would be a million possible strings - too many to put in the auto complete entries. So initially I want to have just the first names as suggestions ("Joe", "John") , and then once the user has typed the first name, ("Joe"), I want to remove the existing auto complete entries and replace them with a new set consisting of the chosen first name followed by the possible surnames ("Joe Bloggs", "Joe Smith"). In order to do this, I tried the following code: void InitializeComboBox() { ComboName.AutoCompleteMode = AutoCompleteMode.SuggestAppend; ComboName.AutoCompleteSource = AutoCompleteSource.CustomSource; ComboName.AutoCompleteCustomSource = new AutoCompleteStringCollection(); ComboName.TextChanged += new EventHandler( ComboName_TextChanged ); } void ComboName_TextChanged( object sender, EventArgs e ) { string text = this.ComboName.Text; string[] suggestions = GetNameSuggestions( text ); this.ComboQuery.AutoCompleteCustomSource.Clear(); this.ComboQuery.AutoCompleteCustomSource.AddRange( suggestions ); } However, this does not work properly. It seems that the call to Clear() causes the auto complete mechanism to "turn off" until the next character appears in the combo box, but of course when the next character appears the above code calls Clear() again, so the user never actually sees the auto complete functionality. It also causes the entire contents of the combo box to become selected, so between every keypress you have to deselect the existing text, which makes it unusable. If I remove the call to Clear() then the auto complete works, but it seems that then the AddRange() call has no effect, because the new suggestions that I add do not appear in the auto complete dropdown. I have been searching for a solution to this, and seen various things suggested, but I cannot get any of them to work - either the auto complete functionality appears disabled, or new strings do not appear. Here is a list of things I have tried: Calling BeginUpdate() before changing the strings and EndUpdate() afterwards. Calling Remove() on all the existing strings instead of Clear(). Clearing the text from the combobox while I update the strings, and adding it back afterwards. Setting the AutoCompleteMode to "None" while I change the strings, and setting it back to "SuggestAppend" afterwards. Hooking the TextUpdate or KeyPress event instead of TextChanged. Replacing the existing AutoCompleteCustomSource with a new AutoCompleteStringCollection each time. None of these helped, even in various combinations. Spence suggested that I try overriding the ComboBox function that gets the list of strings to use in auto complete. Using a reflector I found a couple of methods in the ComboBox class that look promising - GetStringsForAutoComplete() and SetAutoComplete(), but they are both private so I can't access them from a derived class. I couldn't take that any further. I tried replacing the ComboBox with a TextBox, because the auto complete interface is the same, and I found that the behaviour is slightly different. With the TextBox it appears to work better, in that the Append part of the auto complete works properly, but the Suggest part doesn't - the suggestion box briefly flashes to life but then immediately disappears. So I thought "Okay, I'll

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• Problem releasing UIImageView after adding to UIScrollView

  - by Josiah Jordan

  I'm having a memory problem related to UIImageView. After adding this view to my UIScrollView, if I try to release the UIImageView the application crashes. According to the stack trace, something is calling [UIImageView stopAnimating] after [UIImageView dealloc] is called. However, if I don't release the view the memory is never freed up, and I've confirmed that there remains an extra retain call on the view after deallocating...which causes my total allocations to climb quickly and eventually crash the app after loading the view multiple times. I'm not sure what I'm doing wrong here though...I don't know what is trying to access the UIImageView after it has been released. I've included the relevant header and implementation code below (I'm using the Three20 framework, if that has anything to do with it...also, AppScrollView is just a UIScrollView that forwards the touchesEnded event to the next responder): Header: @interface PhotoHiResPreviewController : TTViewController <UIScrollViewDelegate> { NSString* imageURL; UIImage* hiResImage; UIImageView* imageView; UIView* mainView; AppScrollView* mainScrollView; } @property (nonatomic, retain) NSString* imageURL; @property (nonatomic, retain) NSString* imageShortURL; @property (nonatomic, retain) UIImage* hiResImage; @property (nonatomic, retain) UIImageView* imageView; - (id)initWithImageURL:(NSString*)imageTTURL; Implementation: @implementation PhotoHiResPreviewController @synthesize imageURL, hiResImage, imageView; - (id)initWithImageURL:(NSString*)imageTTURL { if (self = [super init]) { hiResImage = nil; NSString *documentsDirectory = [NSString stringWithString:[NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) lastObject]]; [self setImageURL:[NSString stringWithFormat:@"%@/%@.jpg", documentsDirectory, imageTTURL]]; } return self; } - (void)loadView { [super loadView]; // Initialize the scroll view hiResImage = [UIImage imageWithContentsOfFile:self.imageURL]; CGSize photoSize = [hiResImage size]; mainScrollView = [[AppScrollView alloc] initWithFrame:[UIScreen mainScreen].bounds]; mainScrollView.autoresizingMask = ( UIViewAutoresizingFlexibleWidth | UIViewAutoresizingFlexibleHeight); mainScrollView.backgroundColor = [UIColor blackColor]; mainScrollView.contentSize = photoSize; mainScrollView.contentMode = UIViewContentModeScaleAspectFit; mainScrollView.delegate = self; // Create the image view and add it to the scrollview. UIImageView *tempImageView = [[UIImageView alloc] initWithFrame:CGRectMake(0.0, 0.0, photoSize.width, photoSize.height)]; tempImageView.contentMode = UIViewContentModeCenter; [tempImageView setImage:hiResImage]; self.imageView = tempImageView; [tempImageView release]; [mainScrollView addSubview:imageView]; // Configure zooming. CGSize screenSize = [[UIScreen mainScreen] bounds].size; CGFloat widthRatio = screenSize.width / photoSize.width; CGFloat heightRatio = screenSize.height / photoSize.height; CGFloat initialZoom = (widthRatio > heightRatio) ? heightRatio : widthRatio; mainScrollView.maximumZoomScale = 3.0; mainScrollView.minimumZoomScale = initialZoom; mainScrollView.zoomScale = initialZoom; mainScrollView.bouncesZoom = YES; mainView = [[UIView alloc] initWithFrame:[UIScreen mainScreen].bounds]; mainView.autoresizingMask = ( UIViewAutoresizingFlexibleWidth | UIViewAutoresizingFlexibleHeight); mainView.backgroundColor = [UIColor blackColor]; mainView.contentMode = UIViewContentModeScaleAspectFit; [mainView addSubview:mainScrollView]; // Add to view self.view = mainView; [imageView release]; [mainScrollView release]; [mainView release]; } - (UIView *)viewForZoomingInScrollView:(UIScrollView *)scrollView { return imageView; } - (void)dealloc { mainScrollView.delegate = nil; TT_RELEASE_SAFELY(imageURL); TT_RELEASE_SAFELY(hiResImage); [super dealloc]; } I'm not sure how to get around this. If I remove the call to [imageView release] at the end of the loadView method everything works fine...but I have massive allocations that quickly climb to a breaking point. If I DO release it, however, there's that [UIImageView stopAnimating] call that crashes the application after the view is deallocated. Thanks for any help! I've been banging my head against this one for days. :-P Cheers, Josiah

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• Flex, Papervision3d: basic scenes, cameras, planes issue

  - by user157880

  // Import Papervision3D import org.papervision3d.Papervision3D; import org.papervision3d.scenes.; import org.papervision3d.cameras.; import org.papervision3d.objects.; import org.papervision3d.materials.; public var scene:Scene3D; public var camera:Camera3D; public var target:DisplayObject3D; public var screenshotArray: Array;//array to store pictures public var radius:Number; public var image:Image; private function initPapervision():void { target= new DisplayObject3D(); camera= new Camera3D(target); 1067: Implicit coercion of a value of type org.papervision3d.objects:DisplayObject3D to an unrelated type Number. scene= new Scene3D(thisContainer); 1137: Incorrect number of arguments. Expected no more than 0. scene.addChild( new DisplayObject3D() , "center" ); } public function handleCreationComplete():void { image = new Image(); image.source = "one_t.jpg"; image.maintainAspectRatio = true; image.scaleContent = false; image.autoLoad = false; image.addEventListener(Event.COMPLETE, handleImageLoad); image.load(); initPapervision(); } public function handleImageLoad(event:Event):void { init3D(); // onEnterFrame addEventListener( Event.ENTER_FRAME, loop3D ); addEventListener( MouseEvent.MOUSE_MOVE , handleMouseMove); } public function init3D():void { addScreenshots(20); } public function handleMouseMove(event:MouseEvent):void { camera.y = Math.max( thisContainer.mouseY*5 , -450 ); } public function addScreenshots(planeCount:Number):void { var obj:DisplayObject3D = scene.getChildByName ("center"); screenshotArray = new Array(planeCount); var texture:BitmapData = new BitmapData(image.content.loaderInfo.width, image.content.loaderInfo.height, false, 0); texture.draw(image); // Create texture with a bitmap from the library var materialSpace :MaterialObject3D = new BitmapMaterial(texture); materialSpace.doubleSided = true; materialSpace.smooth = false; radius = 500; camera.z = radius + 50; camera.y = 50; for (var i:Number = 0; i < planeCount; i++ ) { screenshotArray[i] = new Object() <b>screenshotArray[i].plane = new Plane( materialSpace, 100, 100, 2, 2 );</b> 1180: Call to a possibly undefined method Plane. // Position plane var rotation:Number = (360/planeCount)* i ; var rotationRadians:Number = (rotation-90) * (Math.PI/180); screenshotArray[i].rotation = rotation; screenshotArray[i].plane.z = (radius * Math.cos(rotationRadians) ) * -1; screenshotArray[i].plane.x = radius * Math.sin(rotationRadians) * -1; screenshotArray[i].plane.y = 100; screenshotArray[i].plane.lookAt(obj); // Add to scene scene.addChild( screenshotArray[i].plane ); } <b>scene.renderCamera(camera);</b> <i>1061: Call to a possibly undefined method renderCamera through a reference with static type org.papervision3d.scenes:Scene3D.</i> } public function loop3D(event:Event):void { var obj:DisplayObject3D = scene.getChildByName ("center"); for (var i:Number = 0; i < screenshotArray.length ; i++ ) { var rotation:Number = screenshotArray[i].rotation; rotation += (thisContainer.mouseX/50)/(screenshotArray.length/10); var rotationRadians:Number = (rotation-90) * (Math.PI/180); screenshotArray[i].rotation = rotation; screenshotArray[i].plane.z = (radius * Math.cos(rotationRadians) ) * -1; screenshotArray[i].plane.x = radius * Math.sin(rotationRadians) * -1; screenshotArray[i].plane.lookAt(obj); } //now lets render the scene <b>scene.renderCamera(camera);</b> <i>1061: Call to a possibly undefined method renderCamera through a reference with static type org.papervision3d.scenes:Scene3D.</i> } ]]

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• Zoom on multiple areas in d3.js

  - by t2k32316

  I'm planning to have a geoJSON map inside my svg alongside other svg elements. I would like to be able to zoom (zoom+pan) in the map and keep the map in the same location with a bounding box. I can accomplish this by using a clipPath to keep the map within a rectangular area. The problem is that I also want to enable zooming and panning on my entire svg. If I do d3.select("svg").call(myzoom); this overrides any zoom I applied to my map. How can I apply zoom to both my entire svg and to my map? That is, I want to be able to zoom+pan on my map when my mouse is in the map's bounding box, and when the mouse is outside the bounding box, zoom+pan on the entire svg. Here's example code: http://bl.ocks.org/nuernber/aeaac0e8edcf7ca93ade. (how do I get around the cross domain issue to load the map?) <svg id="svg" width="640" height="480" xmlns="http://www.w3.org/2000/svg" version="1.1"> <defs> <clipPath id="rectClip"> <rect x="150" y="25" width="400" height="400" style="stroke: gray; fill: none;"/> </clipPath> </defs> <g id="outer_group"> <circle cx="100" cy="50" r="40" stroke="black" stroke-width="2" fill="red" /> <g id="svg_map" style="clip-path: url(#rectClip);"> </g> </g> </svg><br/> <script type="text/javascript"> var svg = d3.select("#svg_map"); var mapGroup = svg.append("g"); var projection = d3.geo.mercator(); var path = d3.geo.path().projection(projection); var zoom = d3.behavior.zoom() .translate(projection.translate()) .scale(projection.scale()) .on("zoom", zoomed); mapGroup.call(zoom); var pan = d3.behavior.zoom() .on("zoom", panned); d3.select("svg").call(pan); mapGroup.attr("transform", "translate(200,0) scale(2,2)"); d3.json("ne_110m_admin_0_countries/ne_110m_admin_0_countries.geojson", function(collection) { mapGroup.selectAll("path").data(collection.features) .enter().append("path") .attr("d", path) .attr("id", function(d) { return d.properties.name.replace(/\s+/g, "")}) .style("fill", "gray").style("stroke", "white").style("stroke-width",1); } ); function panned() { var x = d3.event.translate[0]; var y = d3.event.translate[1]; d3.select("#outer_group").attr("transform", "translate("+x+","+y+") scale(" + d3.event.scale + ")"); } function zoomed() { previousScale = d3.event.scale; projection.translate(d3.event.translate).scale(d3.event.scale); translationOffset = d3.event.translate; mapGroup.selectAll("path").attr("d", path); } </script>

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• Django - no module named app

  - by Koran

  Hi, I have been trying to get an application written in django working - but it is not working at all. I have been working on for some time too - and it is working on dev-server perfectly. But I am unable to put in the production env (apahce). My project name is apstat and the app name is basic. I try to access it as following Blockquote http://hostname/apstat But it shows the following error: MOD_PYTHON ERROR ProcessId: 6002 Interpreter: 'domU-12-31-39-06-DD-F4.compute-1.internal' ServerName: 'domU-12-31-39-06-DD-F4.compute-1.internal' DocumentRoot: '/home/ubuntu/server/' URI: '/apstat/' Location: '/apstat' Directory: None Filename: '/home/ubuntu/server/apstat/' PathInfo: '' Phase: 'PythonHandler' Handler: 'django.core.handlers.modpython' Traceback (most recent call last): File "/usr/lib/python2.6/dist-packages/mod_python/importer.py", line 1537, in HandlerDispatch default=default_handler, arg=req, silent=hlist.silent) File "/usr/lib/python2.6/dist-packages/mod_python/importer.py", line 1229, in _process_target result = _execute_target(config, req, object, arg) File "/usr/lib/python2.6/dist-packages/mod_python/importer.py", line 1128, in _execute_target result = object(arg) File "/usr/lib/pymodules/python2.6/django/core/handlers/modpython.py", line 228, in handler return ModPythonHandler()(req) File "/usr/lib/pymodules/python2.6/django/core/handlers/modpython.py", line 201, in __call__ response = self.get_response(request) File "/usr/lib/pymodules/python2.6/django/core/handlers/base.py", line 134, in get_response return self.handle_uncaught_exception(request, resolver, exc_info) File "/usr/lib/pymodules/python2.6/django/core/handlers/base.py", line 154, in handle_uncaught_exception return debug.technical_500_response(request, *exc_info) File "/usr/lib/pymodules/python2.6/django/views/debug.py", line 40, in technical_500_response html = reporter.get_traceback_html() File "/usr/lib/pymodules/python2.6/django/views/debug.py", line 114, in get_traceback_html return t.render(c) File "/usr/lib/pymodules/python2.6/django/template/__init__.py", line 178, in render return self.nodelist.render(context) File "/usr/lib/pymodules/python2.6/django/template/__init__.py", line 779, in render bits.append(self.render_node(node, context)) File "/usr/lib/pymodules/python2.6/django/template/debug.py", line 81, in render_node raise wrapped TemplateSyntaxError: Caught an exception while rendering: No module named basic Original Traceback (most recent call last): File "/usr/lib/pymodules/python2.6/django/template/debug.py", line 71, in render_node result = node.render(context) File "/usr/lib/pymodules/python2.6/django/template/debug.py", line 87, in render output = force_unicode(self.filter_expression.resolve(context)) File "/usr/lib/pymodules/python2.6/django/template/__init__.py", line 572, in resolve new_obj = func(obj, *arg_vals) File "/usr/lib/pymodules/python2.6/django/template/defaultfilters.py", line 687, in date return format(value, arg) File "/usr/lib/pymodules/python2.6/django/utils/dateformat.py", line 269, in format return df.format(format_string) File "/usr/lib/pymodules/python2.6/django/utils/dateformat.py", line 30, in format pieces.append(force_unicode(getattr(self, piece)())) File "/usr/lib/pymodules/python2.6/django/utils/dateformat.py", line 175, in r return self.format('D, j M Y H:i:s O') File "/usr/lib/pymodules/python2.6/django/utils/dateformat.py", line 30, in format pieces.append(force_unicode(getattr(self, piece)())) File "/usr/lib/pymodules/python2.6/django/utils/encoding.py", line 71, in force_unicode s = unicode(s) File "/usr/lib/pymodules/python2.6/django/utils/functional.py", line 201, in __unicode_cast return self.__func(*self.__args, **self.__kw) File "/usr/lib/pymodules/python2.6/django/utils/translation/__init__.py", line 62, in ugettext return real_ugettext(message) File "/usr/lib/pymodules/python2.6/django/utils/translation/trans_real.py", line 286, in ugettext return do_translate(message, 'ugettext') File "/usr/lib/pymodules/python2.6/django/utils/translation/trans_real.py", line 276, in do_translate _default = translation(settings.LANGUAGE_CODE) File "/usr/lib/pymodules/python2.6/django/utils/translation/trans_real.py", line 194, in translation default_translation = _fetch(settings.LANGUAGE_CODE) File "/usr/lib/pymodules/python2.6/django/utils/translation/trans_real.py", line 180, in _fetch app = import_module(appname) File "/usr/lib/pymodules/python2.6/django/utils/importlib.py", line 35, in import_module __import__(name) ImportError: No module named basic My settings.py is as follows: INSTALLED_APPS = ( 'django.contrib.auth', 'django.contrib.contenttypes', 'django.contrib.sessions', 'django.contrib.sites', 'apstat.basic', 'django.contrib.admin', ) If I remove the apstat.basic, it goes through, but that is not a solution. Is it something I am doing in apache? My apache - settings are - <VirtualHost *:80> ServerAdmin webmaster@localhost DocumentRoot /home/ubuntu/server/ <Directory /> Options None AllowOverride None </Directory> <Directory /home/ubuntu/server/apstat> AllowOverride None Order allow,deny allow from all </Directory> <Location "/apstat"> SetHandler python-program PythonHandler django.core.handlers.modpython SetEnv DJANGO_SETTINGS_MODULE apstat.settings PythonOption django.root /home/ubuntu/server/ PythonDebug On PythonPath "['/home/ubuntu/server/'] + sys.path" </Location> </VirtualHost> I have now sat for more than a day on this. If someone can help me out, it would be very nice.

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• Understanding Node.js and concept of non-blocking I/O

  - by Saif Bechan

  Recently I became interested in using Node.js to tackle some of the parts of my web-application. I love the part that its full JavaScript and its very light weight so no use anymore to call an JavaScript-PHP call but a lighter JavaScript-JavaScript call. I however do not understand all the concepts explained. Basic concepts Now in the presentation for Node.js Ryan Dahl talks about non-blocking IO and why this is the way we need to create our programs. I can understand the theoretical concept. You just don't wait for a response, you go ahead and do other things. You make a callback for the response, and when the response arrives millions of clock-cycles later, you can fire that. If you have not already I recommend to watch this presentation. It is very easy to follow and pretty detailed. There are some nice concepts explained on how to write your code in a good manner. There are also some examples given and I am going to work with the basic example given. Examples The way we do thing now: puts("Enter your name: "); var name = gets(); puts("Name: " + name); Now the problem with this is that the code is halted at line 1. It blocks your code. The way we need to do things according to node puts("Enter your name: "); gets(function (name) { puts("Name: " + name); }); Now with this your program does not halt, because the input is a function within the output. So the programs continues to work without halting. Questions Now the basic question I have is how does this work in real-life situations. I am talking here for the use in web-applications. The application I am writing does I/O, bit is still does it in am blocking matter. I think that most of the time, if not all, you need to block, because you have to wait on what the response is you have to work with. When you need to get some information from the database, most of the time this data needs to be verified before you can further with the code. Example 1 If you take a login for example. You have to wait for the database to response to return, because you can not do anything else. I can't see a way around this without blocking. Example 2 Going back to the basic example. The use just request something from a database which does not need any verification. You still have to block because you don't have anything to do more. I can not come up with a single example where you want to do other things while you wait for the response to return. Possible answers I have read that this frees up recourses. When you program like this it takes less CPU or memory usage. So this non-blocking IO is ONLY meant to free up recourses and does not have any other practical use. Not that this is not a huge plus, freeing up recourses is always good. Yet I fail to see this as a good solution. because in both of the above examples, the program has to wait for the response of the user. Whether this is inside a function, or just inline, in my opinion there is a program that wait for input. Resources I looked at I have looked at some recourses before I posted this question. They talk a lot about the theoretical concept, which is quite clear. Yet i fail to see some real-life examples where this is makes a huge difference. Stackoverflow: What is in simple words blocking IO and non-blocking IO? Blocking IO vs non-blocking IO; looking for good articles tidy code for asynchronous IO Other recources: Wikipedia: Asynchronous I/O Introduction to non-blocking I/O The C10K problem

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• Python bindings for a vala library

  - by celil

  I am trying to create python bindings to a vala library using the following IBM tutorial as a reference. My initial directory has the following two files: test.vala using GLib; namespace Test { public class Test : Object { public int sum(int x, int y) { return x + y; } } } test.override %% headers #include <Python.h> #include "pygobject.h" #include "test.h" %% modulename test %% import gobject.GObject as PyGObject_Type %% ignore-glob *_get_type %% and try to build the python module source test_wrap.c using the following code build.sh #/usr/bin/env bash valac test.vala -CH test.h python /usr/share/pygobject/2.0/codegen/h2def.py test.h > test.defs pygobject-codegen-2.0 -o test.override -p test test.defs > test_wrap.c However, the last command fails with an error $ ./build.sh Traceback (most recent call last): File "/usr/share/pygobject/2.0/codegen/codegen.py", line 1720, in <module> sys.exit(main(sys.argv)) File "/usr/share/pygobject/2.0/codegen/codegen.py", line 1672, in main o = override.Overrides(arg) File "/usr/share/pygobject/2.0/codegen/override.py", line 52, in __init__ self.handle_file(filename) File "/usr/share/pygobject/2.0/codegen/override.py", line 84, in handle_file self.__parse_override(buf, startline, filename) File "/usr/share/pygobject/2.0/codegen/override.py", line 96, in __parse_override command = words[0] IndexError: list index out of range Is this a bug in pygobject, or is something wrong with my setup? What is the best way to call code written in vala from python? EDIT: Removing the extra line fixed the current problem, but now as I proceed to build the python module, I am facing another problem. Adding the following C file to the existing two in the directory: test_module.c #include <Python.h> void test_register_classes (PyObject *d); extern PyMethodDef test_functions[]; DL_EXPORT(void) inittest(void) { PyObject *m, *d; init_pygobject(); m = Py_InitModule("test", test_functions); d = PyModule_GetDict(m); test_register_classes(d); if (PyErr_Occurred ()) { Py_FatalError ("can't initialise module test"); } } and building with the following script build.sh #/usr/bin/env bash valac test.vala -CH test.h python /usr/share/pygobject/2.0/codegen/h2def.py test.h > test.defs pygobject-codegen-2.0 -o test.override -p test test.defs > test_wrap.c CFLAGS="`pkg-config --cflags pygobject-2.0` -I/usr/include/python2.6/ -I." LDFLAGS="`pkg-config --libs pygobject-2.0`" gcc $CFLAGS -fPIC -c test.c gcc $CFLAGS -fPIC -c test_wrap.c gcc $CFLAGS -fPIC -c test_module.c gcc $LDFLAGS -shared test.o test_wrap.o test_module.o -o test.so python -c 'import test; exit()' results in an error: $ ./build.sh ***INFO*** The coverage of global functions is 100.00% (1/1) ***INFO*** The coverage of methods is 100.00% (1/1) ***INFO*** There are no declared virtual proxies. ***INFO*** There are no declared virtual accessors. ***INFO*** There are no declared interface proxies. Traceback (most recent call last): File "<string>", line 1, in <module> ImportError: ./test.so: undefined symbol: init_pygobject Where is the init_pygobject symbol defined? What have I missed linking to?

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• SQLAlchemy session management in long-running process

  - by codeape

  Scenario: A .NET-based application server (Wonderware IAS/System Platform) hosts automation objects that communicate with various equipment on the factory floor. CPython is hosted inside this application server (using Python for .NET). The automation objects have scripting functionality built-in (using a custom, .NET-based language). These scripts call Python functions. The Python functions are part of a system to track Work-In-Progress on the factory floor. The purpose of the system is to track the produced widgets along the process, ensure that the widgets go through the process in the correct order, and check that certain conditions are met along the process. The widget production history and widget state is stored in a relational database, this is where SQLAlchemy plays its part. For example, when a widget passes a scanner, the automation software triggers the following script (written in the application server's custom scripting language): ' wiget_id and scanner_id provided by automation object ' ExecFunction() takes care of calling a CPython function retval = ExecFunction("WidgetScanned", widget_id, scanner_id); ' if the python function raises an Exception, ErrorOccured will be true ' in this case, any errors should cause the production line to stop. if (retval.ErrorOccured) then ProductionLine.Running = False; InformationBoard.DisplayText = "ERROR: " + retval.Exception.Message; InformationBoard.SoundAlarm = True end if; The script calls the WidgetScanned python function: # pywip/functions.py from pywip.database import session from pywip.model import Widget, WidgetHistoryItem from pywip import validation, StatusMessage from datetime import datetime def WidgetScanned(widget_id, scanner_id): widget = session.query(Widget).get(widget_id) validation.validate_widget_passed_scanner(widget, scanner) # raises exception on error widget.history.append(WidgetHistoryItem(timestamp=datetime.now(), action=u"SCANNED", scanner_id=scanner_id)) widget.last_scanner = scanner_id widget.last_update = datetime.now() return StatusMessage("OK") # ... there are a dozen similar functions My question is: How do I best manage SQLAlchemy sessions in this scenario? The application server is a long-running process, typically running months between restarts. The application server is single-threaded. Currently, I do it the following way: I apply a decorator to the functions I make avaliable to the application server: # pywip/iasfunctions.py from pywip import functions def ias_session_handling(func): def _ias_session_handling(*args, **kwargs): try: retval = func(*args, **kwargs) session.commit() return retval except: session.rollback() raise return _ias_session_handling # ... actually I populate this module with decorated versions of all the functions in pywip.functions dynamically WidgetScanned = ias_session_handling(functions.WidgetScanned) Question: Is the decorator above suitable for handling sessions in a long-running process? Should I call session.remove()? The SQLAlchemy session object is a scoped session: # pywip/database.py from sqlalchemy.orm import scoped_session, sessionmaker session = scoped_session(sessionmaker()) I want to keep the session management out of the basic functions. For two reasons: There is another family of functions, sequence functions. The sequence functions call several of the basic functions. One sequence function should equal one database transaction. I need to be able to use the library from other environments. a) From a TurboGears web application. In that case, session management is done by TurboGears. b) From an IPython shell. In that case, commit/rollback will be explicit. (I am truly sorry for the long question. But I felt I needed to explain the scenario. Perhaps not necessary?)

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• WCF .svc Accessible Over HTTP But Accessing WSDL Causes "Connection Was Reset"

  - by Wolfwyrd

  I have a WCF service which is hosted on IIS6 on a Win2003 SP2 machine. The WCF service is hosting correctly and is visible over HTTP giving the usual "To test this service, you will need to create a client and use it to call the service" message. However accessing the .svc?WSDL link causes the connection to be reset. The server itself is returning a 200 in the logs for the WSDL request, an example of which is shown here, the first call gets a connection reset, the second is a successful call for the .svc file. 2010-04-09 11:00:21 W3SVC6 MACHINENAME 10.79.42.115 GET /IntegrationService.svc wsdl 80 - 10.75.33.71 HTTP/1.1 Mozilla/4.0+(compatible;+MSIE+7.0;+Windows+NT+5.1;+.NET+CLR+2.0.50727;+.NET+CLR+1.1.4322;+.NET+CLR+1.0.3705;+InfoPath.1;+.NET+CLR+3.0.04506.30;+MS-RTC+LM+8;+.NET+CLR+3.0.4506.2152;+.NET+CLR+3.5.30729;) - - devsitename.mydevdomain.com 200 0 0 0 696 3827 2010-04-09 11:04:10 W3SVC6 MACHINENAME 10.79.42.115 GET /IntegrationService.svc - 80 - 10.75.33.71 HTTP/1.1 Mozilla/5.0+(Windows;+U;+Windows+NT+5.1;+en-GB;+rv:1.9.1.9)+Gecko/20100315+Firefox/3.5.9+(.NET+CLR+3.5.30729) - - devsitename.mydevdomain.com 200 0 0 3144 457 265 My Web.Config looks like: <system.serviceModel> <serviceHostingEnvironment > <baseAddressPrefixFilters> <add prefix="http://devsitename.mydevdomain.com" /> </baseAddressPrefixFilters> </serviceHostingEnvironment> <behaviors> <serviceBehaviors> <behavior name="My.Service.IntegrationServiceBehavior"> <serviceMetadata httpGetEnabled="true" /> <serviceDebug includeExceptionDetailInFaults="false" /> </behavior> </serviceBehaviors> </behaviors> <services> <service behaviorConfiguration="My.Service.IntegrationServiceBehavior" name="My.Service.IntegrationService"> <endpoint address="" binding="wsHttpBinding" contract="My.Service.Interfaces.IIntegrationService" bindingConfiguration="NoSecurityConfig" /> <endpoint address="mex" binding="mexHttpBinding" contract="IMetadataExchange" /> </service> </services> <bindings> <wsHttpBinding> <binding name="NoSecurityConfig"> <security mode="None" /> </binding> </wsHttpBinding> </bindings> </system.serviceModel> I'm pretty much stumped by this one. It works fine through the local dev server in VS2008 but fails after deployment. For further information, the targeted machine does not have a firewall (it's on the internal network) and the logs show the site thinks it's fine with 200 OK responses. I've also tried updating the endpoint with the full URL to my service however it still makes no difference. I have looked into some of the other options - creating a separate WSDL manually and exposing it through the metadata properties (really don't want to do that due to the maintenance issues). If anyone can offer any thoughts on this or any other workarounds it would be greatly appreciated.

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